60GB - SOME Titles are backwards compatible, but not all IIRC. It has a built-in chip for BW capatibility and can cause older games to skip and shake during gameplay. Not sure if the 60Gb has an upscaler for older titles or not.
80GB - 100% BW Compatible w/ Updates. Download the latest updates via PS Online or DL them onto a flashdrive then upload onto your PS3 via the instructions availabled on the official website. Takes about 10 minutes. Also, the 80GB has a built-in upscaler to make your older games run smoother and look prettier. It's a very noticeable difference on some titles (.hack//G.U. for example). Good luck finding one though. Your best bet would be via Gamestop's official website. I found one in Georgia (Marietta) and picked it up immediately because other people were calling for it too.
I've had my 80GB for a few months now and have 0 complaints with PS, PS2, or PS3 titles.
