I'm still using my Q6600 (stock) but looking to upgrade now because I get a lot of lag in big battles when playing Diablo 3, even on low settings and resolutions, making me think the CPU is my bottleneck not my HD6870. I also play Starcraft 2 and Civ 5, which are both CPU intensive in big battles (especially near the end game of Civ 5). The cost is putting me off tho, over £300 to upgrade, especially if i want to keep the machine as quiet as it is at the moment.