Assuming you don't have a stellar PC, I'm getting Dragon Age, and that's probably the best game you can get for your buck right now, and looks amazing. If not that, there's Oblivion (though this is too GRAND in scope for me), and Fallout 3 (which was pretty awesome, but not AS awesome as everyone makes it to be).
OH MAN, almost forgot, DEMON'S SOULS. THAT's the game you want, it's freakin' amazing in any way you look at it: graphics, challenge, length, atmosphere, gameplay, it's all perfected.