what kind of game?
For a FPS I'd say FEAR or Bf2. FEAR has an awesome single player, the graphics are the best I've seen. BF2 is a very good multiplayer game, though ATM there is still some bugs. If u are going for a multiplayer game then get BF2, the multiplayer is all the game is about.
If u want an RPG I'd take Guild Wars instead of WoW.