Does your motherboard support Core2 Quad? If it does then the Q6600 is a fantastic choice.

I would try some ram with a slightly higher frequency, perhaps 800MHz. This is what I stuck in Chazlene's PC a while back - and it's only a couple of quid more!

Oh, and I have always had great experiences with Overclockers.co.uk and Ebuyer.com, although the only thing that I would say really separates them is the superior RMA policy at Ebuyer.