I played burnout on the 360 and loved it. great game
Call of Duty 4 (first person Shooter)
Rainbow 6 Vegas 1 and 2
Grand Theft Auto 4 just came out
Assassins Creed
The Orange Box (halflife 2)
Rock Band
Ninja Gaiden Sigma
Elder Scrolls Oblivion
That ought to be enough for your first couple days
Im a 360 Guy but these are all good games...