It shouldn't be so much a motherboard issue as a CPU issue. Server 2008 R2 is only available in 64-bit form, so you'll need a 64-bit capable processor. And if you want to use Hyper-V then you'll need a CPU with virtualization support.
Thanks for the answer.
After doing more research yesterday, I realized that my question was a pretty ignorant one. But hey, I was ignorant when I asked it
I ended up getting an Intel I7 920 processor with 12 gigs of RAM. I'm planning to run several VM's for testing purposes on the box, so I needed more than 6. 12 seemed like overkill, but 6 wasn't enough, so I had to go with 12.
Anyways, thanks for the answer, and I think I'm good to go now. My computer is ready tomorrow, so I'll find out then.