The average optimal number of CPU cores suggested by the test results is 2.75, showing a clear trend towards at least three CPU cores.The question of whether the CPU or GPU is most important is easily answered. If you don't have a multi-core CPU, then upgrade it. If you have a dual-core CPU at around 3 GHz, then invest your money into a graphics card, as most games are GPU-limited. This is not something that will change with new DirectX 11 games.
Hit an after market cooler as the stock speeds of a Q6600 is a tad low and clock it, state what PSU model u on and something like a gtx 460/hd 6850 would see you net huge gains in your games hehe