xbox 360 is easier to hack and get illegal games, surely thats high on your list?
Depends if you are into high def movies, if you are then the ps3 makes sense, if not then go for the games machine, will need to add a wireless adapter though and a play and charge kit.
BTW, i wouldn't get a 20gb hdd one as its too small, its only 13gb after formatting and the backwards compatibility stuff and i am constantly deleting things from mine to download new demos.