If you need an additional controller you HAVE yo buy this http://www.gamestop.com/ps3/games/god-of-war-saga-deep-red-dualshock-3-wireless-controller/105842 It's an amazing deal, a new controller would cost you at least $40 on Amazon now (normally $54.99) so you're getting 5 of the best games ever for just $20.
Also stick to the 250GB model and although I'm not subscribed to Playstation Plus because I game more on the Xbox 360 it does seems like a great service based on what I've heard and all the discounts and free games you'll get so I recommend that too.
If you're getting a PS3 it should be primarily to play the exclusives since the Xbox 360 almost always has the superior multi-platform version (not including PC) and I think the Xbox 360 controller is more comfortable which is why I'd rather play on it most of the time. If you can't think of at least 15 exclusive games you want to play then I wouldn't bother with the PS3, I myself only bought a PS3 for God of War III and it was worth it for me but that's probably because I'm a crazed fan, I'd advise anyone else to make sure they're interested in enough exclusive games to justify a purchase especially if you already have a Xbox 360.







