If you haven't did so already, Install Windows Media Player 11 for Windows XP (Note that Validation is required, so ensure you have a legal version of Windows).

Now, start it up and click on the arrow below the Library tab.

Now click on "Media sharing".

You will get this:

Set same sharing settings as I have. Now go to your PS3 and sellect "Search for mediaservers".
It should bring up one server called "Your PC name: Your account name:''

Example: "MASTER_PC_SERVER: Administrator:".

Now return to the WMP11 screen and you will see a new device is added.

Select it and click on Allow.

Reboot your PS3 if it says you can't view the content. Now, import media into WMP and you are done!