I'd get 4GB of PC6400 (2x2GB) You won't be needing dominator ram with the Q6600 and it would take 3.6GHz just to be at the stock speeds of PC6400 RAM and Q6600's don't go much further than that.
It's also about the same price and you get twice as much
For a cooler the best around seem to still be the Thermalright Ultima 90 and 120 Extreme. That said we do hear about flakey results which is often due to an uneven base. This means you will have to start thinking about lapping it if you want to overclock which is a lot of effort (This problem might just be the Extreme though).
I personally use scythe and have had 3 of the current Ninja rev B's for recent builds which have all been perfect.
They also do the well regarded infinity (or mugen) and the mine for a few pounds less which the hexus review proved is very good but others review rate it slightly lower.
120mm fans. Scythe S-Flex 1200 and 1600 are very good fans.
Scan also sell xigmatek fans for around £4.50 which seems to work very well in my mates pc adding no extra noise but providing higher overclocks than his s-flex 1600 (With the thermalright 120 extreme)