chaddeus,
I'm going P35 chipset with an ASUS P5K-E. I looked for awhile at the x38 chipset mobos, but from all that I read, they weren't much better performing than the P35s if you use DDR2 memory. It seems that most gains using x38 come from using DDR3, and right now, that's too expensive. Most of the x38 boards came out with high price tags, as well...
As for P35s, I looked at Abit IP35-E and Pro, both pretty good boards, but in the final analysis stayed with ASUS, which I've used pretty much over the past couple of years.
Noel