I had the same problem but in a bit of a different situation. I fried my MB/CPU and bought the A7M266 w/ 266fsb 1ghz. Threw that in my box running XP Pro build 2600 and upgraded to bios 1005. It worked just fine, then I decided that I wanted to format and go back to 2000 SP2. So after doing that...reinstalling 2000 gave me nothing but errors at different spots every single time I tried it. I ended up disabling the all of the cache and anything else I could think of that would be a problem and the I proceeded to install Windows 98. After it finally installed about 8 hours later, I decided to switch back to the 1004 bios....which I should have done in the first place, but I wasn't thinking. I'd like to get an XP processor, but with the issues I was having with 1005, I'm just going to wait. I'd love to know if there is a better solution, but I think I'm out of luck on that one.