I have been running on Q6600 for a while now. Of course you probly know that it supplies most of your processes, yet it seems to not be a great CPU for gaming. I might even do your same upgrade. Either that or go with a new i7. If and when you do upgrade, lemme know if there are some significant changes and if you reccomend the upgrade.
<Gigabyte G41M-Combo S-Series, Intel Core 2 Quad 6600 Overclock 3.2 Ghz, NVIDIA GeForce 9800 GTX+ 1GB Memory, 8GB Ram, Seagate 1TB, 850W Corsair, Windows Vista Ultimate x64>