It all depends on what ps3 you have. If you have a nor ps3 there is some information on that hard drive that the system needs. That is why they are able to use a 16mb nor chip is it using the hard drive to store information. Now if you have a NAND ps3 then it uses two 128mb NAND chips to hold all information for the ps3. And data for the user is kept on the hard drive.
But what I would do is make a backup of the system and then install the new hard. Once you install the new hard drive it will ask for you to put in a firmware 4.30 or higher on USB and so it will then write to the hard drive the information you need and then you can install backup after that. This is for a nor ps3. What ps3 model do you have. Thanks
Also forgot to say that yes the ps3 should see old hard drive as long as you don't update the firmware from the old ps3. If you have your old hard drive on 4.30 and you update to 4.31 with new hard drive in there you will have to update the old hard drive with the same. If it is a nor. Thanks