Ho,
If your going for a gaaming rig then I would REALLY recommend a Q6600. They're well worth the extra few quid, and as some of the newer games are Quad Core optomised (Crysis and COD4 being the first) it makes a bit more sense. There's not a lot between the 2 CPU's yet, but that will more than likey change. Also, get a 1333mghz MB, or even wait for the true Penryn chips to come out. Current Quad cores are just 2 x Dual core, the CPU's comming out soon are true Quad core processors which will see a big jump in performance.
Hope you jump on the sever for a game of COD4 soon!!