I would suggest you purchase - Dead Space, Fallout 3 on your new Xbox 360. The 360 version of Dead Space has better FPS from prelim reports and was lead on the 360 anyway. Fallout 3 will also benefit from the full install option on the Xbox 360 and has the DLC (Good if you liked Oblivion) and might be marginally better (Who the hell cares? But it may sway you a little)
Fable 2 is another must buy, and you should consider Mass Effect, Gears of War 1, Definately Halo 3 for the Coop (4 player). Since you have MGS you might want to give Splinter cell a go and if you like JRPGs the best two are Lost Odyssey and Tales of Vesperia.
And just the usual controllers - x however many you want. FYI if you get more than 3 people coming over to play Halo you can buy another unit and system link them to get more players.
Oh yeah, I definately think you should consider condemned 1+2. They are cheap, but very fun!
For Xbox Live - Definately get Braid, Castlecrashers, Geometry Wars II, Duke 3d
Also if you wanna play online go to www.newegg.com and buy yourself a 12month card for $40 with free delivery.
Tease.
