syquest1 :
Well it sounds like the consensus is to over clock my C2D E6600 and not get any new processor.
I will go ahead and put my 2 cents in here. You have a good CPU. OC'ing it will definately boost responsiveness and performance but my overall suggestion is to go with the Q9450. Reasons being is you can OC it to 3.2GHz on air, it will run cooler and use less voltage than even a Q6600 G0. You will also futurproof yourself so you wont have to upgrade again for a while and it will be ready for multicore running Games.
Currently there are only a few games that take advantage of quad core power. HL2 Episode 2(I believe TF2 and Portal do as well but can't verify), Supreme Commander and Crysis. The main difference you will see is that they offload a lot of the physics processing to the CPU leaving the GPU to process those nice polygons and textures.
Also OC'in to 3GHz+ will probably eliminate the bottleneck and show our GPUs true performance in higher resolutions. But even at 2.4GHz the Q6600 screams and I am sure the Q9450 will.
In the end it is up to you. Just take in some advice here, look at the OC guide(should be stickied on the main page) and get a good cooler like the Thermalright Ultra 120 or Zalman 9700CPNS either for your E6600 or either of the C2Q series CPUs as they will help aleviate the heat from the CPU. Don't forget the Artic Silver 5.