i recommend
Oblivion (amazing RPG hard to put down controller, played about 60 hours on that)
Ghost Recong 3 (Offline is amazing if u are good enough to enjoy the hard setting, Online is addictive)
Project Gotham 3 (offline is great but can get repetitive like ealier PGRs, online is alot better)
Call Of Duty 2 (Great offline especially on Veteran (hardest) setting, the best online after they fixed all the bugs and glicthes)
Fight Night 3 (Graphically stunning ( like watching a film (HD TV), very entertaining but repetitive after many plays, online is great also)
i have got the games above and recommend them, i also have "FIFA 06 ROAD TO THE FIFA WORLD CUP" which i think that the gameplay is awful and "MADDEN NFL" which i just cant enjoy because of all the tatics and lack of gameplay.
other games i recommend but dont have
Perfect Dark Zero
Dead or alive 4