I'm running Oblivion at decent levels using a 1.83 duo core with 2GB of ram and ATi1600. You can tweak the settings to increase the threads ( see gamespot for a good article on this) and aply some mods. It's an execellent game, still amazes me what will run in this box, bioshock, stalker, fear and cod4 run (on lower resolutions) fine.