2 gigs, nice. That would last you quite a while.
For motherboards, I recommand that you get a board with nforce4 SLI so you have a SLI board in case you want to put in another 7800 GTX when prices go down, at least what's what I'm doing and I think it's a good idea...
Anyways, for motherboards, I'm looking at an ASUS A8N-SLI. It uses Socket 939, so will be compatible with either processor, and it's SLI. Plus you can get one for around $130 online. The DFI Lanparty boards are suppose to be of high quality too. If you want to spend >$100, the MSI K8N Neo4 Platnium boards are pretty good.