Microsoft has been developing Windows 7 under a shroud of secrecy worthy of Apple, and it's led to a rash of rumors and unfounded expectations.

So let us state for the record: Windows 7 doesn't have a new kernel, it doesn't run in the cloud and it's not based on Midori (a research project focused on writing an OS in managed code).

In fact, Windows 7 uses the same driver model as Vista - and even refers to itself as version 6.1. We've got our hands on the Milestone Three (M3) pre-beta release of Windows 7, so read on to find out exactly what to expect from Microsoft's newest OS.

Windows 7's philosophy

You can get a good idea about future versions of Windows by looking at the progress of Office under Steven Sinofsky, now Senior Vice President of the Windows and Windows Live engineering group. The changes that he's made to the Windows team aren't just about what new features go into Windows; they're about the whole way that Windows is developed.

These changes are definitely a response to what happened with Vista, which he sees as a learning experience: "As engineers, you have to have some things that don't go as well as you would have liked and you have to go and learn what to prevent. We just really weren't ready when the product [was released]. We did a lot of work, we just didn't do enough and we didn't do the right kind of work, so we had to go and improve that."

The improvements that Sinofsky speaks of are centred within three key areas: the process of developing Windows; the concepts behind 7's key design principles; and the rebuilding of relationships with original equipment manufacturers (OEMs) that were soured by Vista. Culturally, the Windows team is working in a very different way to previous incarnations.

Instead of one team creating Tablet PC features, another team working on Media Center features and yet another team working on core Windows pieces (with none of those teams getting together and interoperating correctly at the end), one team now owns an entire feature across all the platforms from start to finish.

The new development process is more structured and more realistic about what can be achieved in three years, and key to this new process is ensuring that every feature included in each of the internal milestones is usable by the end of it. Compare that concept to what happened to the 'three pillars' of Vista. Indigo - the Windows Communication Foundation -does what was promised, but so far it's used mainly by Microsoft's own business applications.

The Windows Presentation Foundation that shipped in Vista was ripped out and rewritten at the last minute because it was deemed not to work well enough. And WinFS - the long-awaited Object File System for creating an database of metadata and extensible schemas for different types of data - was shuffled off into SQL Server because Search fulfilled the needs of most users.

Principles for 7

The vision for Windows 7 doesn't sound like a snappy marketing slogan yet. Even Mike Nash, the Vice President for Windows Product Management, doesn't have one. He says: "The things you do today on Windows, Windows 7 makes easier; and the things you always dreamed of doing [are made] possible."

It's back to basics on the engineering side, says Gabriel Aul, the Program Manager in charge of Windows Performance. "Quality is a fundamental. Device compatibility is important. Other things are important too - like aesthetics, ease of use and the Help content - but this is really the foundation everything else has to build upon." That might sound obvious, but it's something that Microsoft needs to promise - and deliver.

What will 7 look like?

This time, a key concern for Microsoft in terms of design is the Windows user experience. To make this happen, there's been a bit of a re-shuffle; Sinofsky isn't the only person to move from the Office team to Windows. Julie Larson-Green, the person responsible for introducing the ribbon interface to Office 2007, is now Corporate Vice President of Program Management for the Windows Experience.

A handful of accessories (including WordPad, Movie Maker and Paint) will get a version of the ribbon, but it's not the look of Office 2007 that you'll see in Windows 7: it's the principle of putting new features in the right place and making existing features easy to find.

The changes to the new Windows 7 user interface will be subtle, but they reflect a handful of design principles aimed at countering the perception that PCs are confusing and difficult to use. For example, there are six different methods that you can use to open up your email client in Vista, including icons on the desktop, in the taskbar and in the system tray as well as on the Start menu.

Windows 7 replaces the majority of those with an icon on the taskbar that launches Outlook and gets you back to it once it's open. This concept is repeated for many applications, de-cluttering the desktop. And if you hover your cursor over the program's icon, you'll get a preview of the running program that can show the multiple windows inside the app. So you can see all of the tabs in IE8 without having to switch into the browser itself, for example.

Another addition to the user interface is the Jump List, which shows recent documents. If the app supports it, the Jump List can provide shortcuts to documents that you open often, your most frequently used tasks in an application (such as composing an email) and even the last track that you heard in Windows Media Player.

Microsoft decided not to include an extra icon to get to the Jump List; it turned out to be distracting and easy to click when you didn't want to. This sort of decision is symptomatic of the principle that Windows 7 should be quieter than previous Windows OSes.

Examples of the new 'quieter' Windows model are everywhere. System messages go into the new Solution Center instead of popping up and getting in your way; applications can only show balloon messages in the notification area; and new icons that try to put themselves into the notification area are kept in a hidden list until you choose to put them in the tray. The UAC is still there, but it's now much less intrusive, and there's a slider that allows you to choose what you get elevation requests for. Other changes to the user interface are focused on making Windows 7 more intuitive to use.

Small changes to the Explorer window mean that you can see more pictures in the same space. Move the mouse into the right-hand corner of the screen and your windows turn transparent so that you can see the desktop (which can now have gadgets all over it instead of just in the sidebar). Drag a window to the top of the screen and it maximises; drag it to the side and it takes up half of the screen so that you can easily see two windows side by side. These features are only partly about the way Windows 7 looks; a lot of them are about getting Windows out of the way.

Under the bonnet

Windows 7 uses the same kernel as Windows Server 2008 R2 (which is based on the kernel used in Vista, Server 2008 and Vista SP1), but that doesn't mean that there haven't been any changes. Similarly, Mac OS X and the iPhone may use the Mach kernel that Rick Rashid (the head of Microsoft Research) wrote 25 years ago, but that doesn't mean that Apple's operating system and revolutionary smartphone are at all comparable to the technology that the code was originally written for. The code within both kernels has been replaced and updated over the years.

The Windows 7 kernel has been through a code verifier that proves around 100 key properties, and it's been updated based on those tests. Low-level kernel locks that could block the Start menu and taskbar have been minimised to improve the speed of the user interface, and a new 'pre-wait' state for threads means that they're not held up by the dispatcher lock. There's also finer granularity in the page file database, which means that threads aren't waiting for memory locks as often.

These changes matter more for parallel multithreaded applications on massively multiprocessor and multicore systems with many gigabytes of memory (like Intel's Larrabee) than for standard desktop software; this is how Windows 7 will scale up to 256 processors. There are fewer changes than Microsoft made to the kernel between XP and Vista, but they're significant for the future.

What Microsoft isn't doing is throwing away the whole kernel - or the whole Vista code base - and starting from scratch. To avoid the same compatibility issues that Vista faced, Microsoft isn't changing the driver model, the graphics sub-system or the componentisation model for Windows 7. Drivers now run in a sandbox, so that a driver hanging won't affect other drivers or apps, but they don't need to be rewritten to support this.

The version number is even staying at 6.1, so software vendors have fewer changes to make in installers. "That's not a statement about the amount of energy put in to this release or the scale or scope of the release," Sinofsky points out. "I don't think it's necessary to break everything to have a big change."

New features

M3 doesn't have all of the features that will be in Windows 7, but it does include HomeGroups and Libraries. HomeGroups aim to simplify home networking. Set up a HomeGroup and any other Windows 7 PC on the same network will offer to join it automatically.

Through a HomeGroup, you can share printers, photos and Libraries - virtual folders that work like iTunes or Photo Gallery to give you one view of items in multiple folders. Searches include results from Libraries in the HomeGroup, websites and external drives as well as those on your PC. Keywords are highlighted and you can filter by size, date and other metadata.

Windows Media Player finally comes with a wider range of codecs (DivX, XviD, H.264, AAC, ABC HD and the Flip format), and Media Center supports IPTV and DVB-T. Put a DVD in your PC and it will play automatically. And you can play shared music from a HomeGroup on any PC, or even stream it to a DLNA device like a Sonos ZonePlayer.

Pairing a Bluetooth headset is faster, there's a built-in A2DP stereo driver and sound will be routed to the right device - so you'll get a VoIP call in your ear rather than a system beep.

Microsoft claims that graphics rendering in DirectX 11 will be smoother and quicker. In a demo comparing different methods of rendering without a graphics card, GDI delivered 60fps but with a lot of jagged edges on curves; GDI+ produced smooth edges but only 13fps; and the new Direct2D API (for 2D vector graphics) managed 30fps with smooth curves and anti-aliased edges.

GDI+ will be removed in Windows 7 and GDI will run on the Windows Imaging Component to take advantage of this. There's also a new UIAnimation API for animating under interface elements such as icons.

Using the new DirectWrite text processing system will be twice as fast as rendering text in GDI, according to Microsoft. We can confirm that character edges are certainly much smoother and ClearType now uses blending to smooth horizontal edges to match the way that it uses sub-pixel rendering to smooth vertical lines.

When will 7 be here?

Microsoft isn't saying anything about when Windows 7 will ship apart from "we're going to ship when it's really ready" and "about three years after Vista shipped". A rough estimate based on the latter bit of information would put the proposed release date late in 2009 or early in 2010. The Windows Hardware newsletter revealed that the 2008 Windows Hardware Engineering Conference would be the last one held before Windows 7 ships.

The conference usually takes place in May, but this year it was held in November. Six months is a very short time between conferences when Microsoft has been working so closely with OEM partners (Sinofsky calls them the "primary source of feedback on reliability, compatibility and performance"). But even if Microsoft postpones the conference to the autumn, that would keep Windows 7's release date in 2009.

One thing that's not yet clear is who will be able to get the beta beyond developers and enterprises. Sinofsky has said Microsoft is "going to open up the beta broadly," but he's also indicated that usability testing, feedback from OEMs and telemetry from Windows 7 PCs (showing what apps hang or crash, what drivers are missing, how much memory gets used and so on) are more valuable than the beta processes that Microsoft has used previously. According to Nash, some 'enthusiasts' will also get access to the beta.

The future of Windows

Windows has grown up. We won't see the overblown vision of the Vista release again - where there are more changes to the OS than Microsoft can successfully coordinate and many things need to be rewritten late in the development cycle.

The Windows team is now better structured and more disciplined, and the features that go into a version of Windows will be limited to what can be done in a release cycle. The codename for the next version is Windows 8; plain, predictable and disciplined.

That doesn't mean that Windows itself is going to be boring, however. The PDC slogan is "a solid foundation for new possibilities"; and while Vista veered off toward the less tangible 'possibilities' side of things, Windows 7 is on course to get the foundation right first, offering the architectural and security improvements without the annoyances. Changes to the interface are simple enough not to be confusing, but they reflect a new understanding of how people want to work. They're small changes that will make a big difference.

Virtualisation will certainly be back on the agenda, and multitouch features will expand as the hardware to support it gets cheaper on PC-sized screens rather than just phones and trackpads. But what will really change if the Windows 7 vision comes true is how Windows works with online services, your phone and all of the other devices you use everyday.

The core Office apps will finally move onto the web and your data will be able to follow you around - but Microsoft is still betting that you'll want to work with all of that on a platform with a lot more features than a Web browser. More PlayStation 3 News...