60gb wasnt enough for me, i havent really got an absurd amount of games and only a few mp3s/demos/movies filled up fast. Ive upgraded to 250GB plenty room now :)
But 80GB is a good start, i think if u get the 160GB it will be plenty. Bear in mind ur ps3 can play Movies from DiVX/XViD formats so if you do watch those format movies.
If just for games/demos/mp3s 80GB is enough to start with and vcan easily be upgraded considering HDDs are always getting bigger and coming down in price.