INTRODUCTION:
Changing the hard disk in your PS3 may sound like a tedious task but infact Sony have made this process very simple indeed, and there is even a section in your user manual, unlike changing your xbox 360 hard disk 
. There are a few reasons for upgrading your disk; 2.5" SATA drives are now very cheap, 40, 60 and 80GB is not really enough space for a media box (which is what i use mine for) and you will soon run out of space or constantly have to delete your pictures, movies and music, the new Sony PlayTV can record Digital TV to your PS3 hard disk so storage space on your original disk will soon run out, especially since you can record in 1080p (High Definition), and its always nice to be able to mod your stuff out of the box without invalidating your warranty, you will however need to keep hold of your original hard disk for warranty purposes...
... and that is the reason i chose the 320GB Western Digital My Passport Essential portable USB 2.0 hard disk, the unit contains a single 2.5" SATA hard disk in a neat enclosure, though any 2.5" (5400 / 7200) SATA hard disk should work. Once the PS3 is upgraded i will retro fit the original PS3 drive into the enclosure and use to transfer large files and back up my PS3 - Update 03 April 2008 - SEE FURTHER POSTS
The first thing you will want to do is backup your settings and saved games to an external hard disk or memory stick, you can do this by navigating to Settings>>System Settings>>Backup on your PS3 XMB, make sure you have a drive large enough to hold the backup, alternatively you can copy items idividually (system settings are not saved to the hard disk).
Ensure that your PS3 system is powered off and that all cables are unplugged before proceeding any further, not only does it make the process easier but it will protect your system fomr damage.
PROCEDURE:
Ensure your disk is working prior to taking this step, as this process 'WILL' invalidate your warranty.
There are no screws holding the WD Passport drive in its enclosure and removal of the drive is pretty straight forward, you will need a sharp item like a knife or flat head screw driver in order to remove the drive tray.
Using your sharp implement insert into each end end wiggle gently to prize the tray from the plastic cover:
Carefully pull the drive tray from the plastic casing, it should slide out relatively easily:
Remove the plastic surround from the drive, it should lift out from the top, then pull off each of the rubber spacers:
Slide the hard disk from the metal tray, amd gently pull the SATA-to-USB board from the drive:
You should now have the following components, keep these to one side as you will need them when fitting the PS3 drive:
The next step is to remove the original PS3 hard disk from the PS3, this is very straight forward. Unclip the plastic hard disk cover from the left-hand-side of the PS3, it comes off from the right. Remove the tray retaining screw carefully as not to damage the screw, also take care not to drop the screw inside the PS3:
Lift up the small metal handle and slide the tray gently to the right, then pull the drive out:
Remove the 4 screws from the hard disk tray (take care with these screws as mine were very tight and were hard to remove with a screw driver, i opted for small pliers). Remove the hard disk from the tray and replace with the drive you removed from your WD My Passport Essential (or any 2.52 SATA drive, with storage space greater than your original, else the process would be pointless), and tighten each of the four screws.
Insert the drive tray containing your new disk into your PS3 and slide gently to the left, this process may need a little bit more force to engage the drive connector. Fold down the metal tray handle, and replace the retaining screw. Replace the plastic cover.
You are now ready to power on your PS3, the first thing that came up on my PS3 was a formatting page, select 'Yes' to format your new drive. The formatted space reported by my PS3 was 292GB, a vast improvement on 60GB, just need to copy some media to it now:
You can now use the recovery utility on your PS3 to restore your backed up data.
Remeber to keep your 60GB PS3 disk handy, as you will need to put it back in your PS3 if it ever need to be sent to Sony for repair.
!!! I and The-Port.co.uk accept no responsibilty for damage to or loss of warranty on any of the items described in this article, you accept full reponsibililty !!!