The Athlon X4 880K retails for $95 and it is a quite capable and affordable chip for gaming at 1080p. It comes unlocked so it is easily overclockable and the new improved stock cooler is quiet. The X4-880K has four cores so it's equipped to run the newest game titles. Many of the newest game titles require more than two cores so having a quad-core is a must nowadays if you want to play the latest titles. AMD is shipping the X4 880K with the "near-silent 125W thermal solution" that's actually quite good compared to the previous stock cooler that were too loud.
I don't see the point of buying a dual core processor anymore, some games dont even boot if you have a dual core processor. A buddy of mine has the 860K overclocked to 4.2Ghz and he says it's great for gaming and has no problem with any game he throws at it and plus it's got 4 cores.