Originally Posted by
Vivi22
The 80GB has backwards compatibility for a large number of PS2 games but not all, since it emulates. I can't remember exactly how many, but I think it was in the 1500-2000 title range. I also can't remember how compatible it is with PSX games, but I believe it's compatible with a fairly decent number. The 40GB does have emulated BC for PSX games, but no PS2 support. Since Sony has moved to software emulation though, I'm really not sure why they don't simply offer PS2 support with that model.
Also, with emulation, a lot of games work really well while some will encounter glitches. If BC matters to you in your PS3, then the 60GB model is the only way to go since it has nearly 100% compatibility with PSX and PS2 titles.