Ordering today - advice needed

Greetings!

My PC is used for mostly gaming and it's to that point that games are choppy with my current system. My current spec is:

Athlon XP 4000+
Asus A8N-E
Radeon 4870 X2 (just purchased)
2 Gigs DDR1 memory
2x Western Digital 10k Raptors (Striped)
Windows XP

So I'm looking at purchasing a new motherboard/cpu/memory and looking for advice. It looks like the Q6600 is the best bang for the buck currently so I'm pretty decided on that. What motherboard would you pair with the Q6600? I also need to upgrade the memory and I notice DDR3 is expensive, DDR2 is the best bang for the buck. What memory would you recommend? how much? I plan on upgrading to Vista 64 as well.

Any advice would be appreciated - I'd like to get the order in this afternoon.

I am looking at purchasing the following:

Q6600
http://www.newegg.com/Product/Prod [...] 6819115017

Asus P5Q Pro
http://www.newegg.com/Product/Prod [...] 6813131299

Corsair Dominator 4GB (2x2GB)
http://www.newegg.com/Product/Prod [...] 6820145197

Windows Vista 64

Anyone have any recommendations for 'better' that's either cheaper or a couple dollars more? These parts will be paired with my existing parts which are:
Radeon 4870 X2
2 Western Digital Raptors (Striped)