like you said you just wanna play games and watch movies...there was the 40gb which ive got btw on the cheap for 150 quid but thats another story lol
go for the 80gb which is more than enough even if you want to store demos and songs and videos...80gb will last you plenty of time...previous answers haven't delved into the fact that you can easily replace the hard drive of a ps3...so when the 160b is not enough for some people what next huh...get an 80gb mate and when time comes you can stick in a tb hard drive
p.s why dont u wanna play online...thats the beauty of the ps3 isnt and its free...i never play by myself...