I like my Abit KN8 Ultra. Very stable so far. Running 4600+ X2 and 2 GB. I'm not overclocking other than forcing the 4 ram sticks to their SPD of DDR400 (it wants to throttle it down to 333 with 4 sticks like all mb's want to do with that memory setup).
First complete build and it made me a fan. A few quirks though that I already read about so I was prepared for. But it seemed to be the least problematic of all the boards out there that met my needs.
Oh, and it's just under $100.00.
Joel