The Iwill has bad reviews compared to the Asus DDR board. Then again the Asus has its multipliers locked. I've also heard that the Iwill, with a newer bios is doing much much better..but I who really knows.
If your going to be getting a new 266mhz FSB athlon at 1-1.2ghz I think I would go with the Asus simply because it will already have the multiplier lowered some at default to allow you to get the FSB higher.
I'm still hoping new bios's will fixing the Iwill, simply because its a much cheaper board and has multiplier manipulation. The Asus board looks to set you back at least $200 right now.