Duo Core VS Quad Core processors

Wich of the 2 will perform better for upcoming games like Crysis, Unreal Tournament III and Call of Duty 4?Duo Core VS Quad Core processors
of course the Quad core but the real question is How much? most games there's a very few fps increase going quad core most games are more gpu intense then cpu Duo Core VS Quad Core processors
quad core, but $300 is alot.