quick question on ps3

ok I know they got a lot of differnet models out now. I was wondering about how much space is needed/used of the HD t oload and run the game? I looking a either a 40 gb unit or if I can find a 120 one new unit. I not a heavy gamer mostly some Final fantasy 13 will be the most it get used for at this time. I have most of the other ff games on ps2 and i know i gotot keep the ps2 due t o having ff in ps1 formats and the units are not backwards compatible.

I've had my 80g model for over a year and haven't filled it up. I have around 15g free still. I download a lot of demos but delete after playing a few times. I don't bother saving videos on it, I use TVersity to stream off the PC instead.