I have to say go with a DFI board, I wish I would of gotten one instead of this gigabyte GA-k8nxp that I have.
I have 2 WD SE16 250GB SATAII drives in Raid0, you can buy em for less than $100 now. I get 112MB/Sec sustained tranfer and some pretty insane bursts.
If you are into overclocking at all, why not pick up a opteron 146 cpu and some ddr500 memory. For a ~$180 cpu you can crank the clock up to FX-57 levels (2.8Ghz) on the stock AMD cooler (Its a 4 heatpipe monster). I got a 2GB G.Skill DDR500 from newegg for less than $160 shipped, and it overclocks like a champ (270mhz with stock volts and timings).