As in all new technologys, it will take some trials and errors, and the DDR ram is new...very new. Several have tried it, some succeded...others didn't. Go to the Iwill section of the Amdmb forum to read some. Just about everything that has been tried, has been posted there...
I fired up my KK266-R w/ 1.2ghz Axia T-Bird and 256mb Crucial PC-133 cas 2 for the first time Friday night. This baby rocks!! I had no problems with the first boot. Seems like a stable MOBO. I want to wait a few days before I start OC'ing just to get accustomed to the new PC.
I think Iwill makes some good boards. They left enough room around the CPU for a big HSF w/o hitting any transistors. Pretty good driver and software bundle comes w/ it.
Good luck on your choice of MOBO's.