I have an Athlon 1.2 @ 1266, Abit KT7A (KT133A), SBLive, GF2 Ultra, Windows 2000, and an IBM 45GB ATA100 HD. Everything works fine. However, Window 2000 assumes you have an ATA66 HD which causes a huge slowdown (at least with the hardware I have..), but that can be fixed by going here: http://support.microsoft.com/support/kb/articles/q260/2/33.asp
Also, a little problem with Athlon/2K but it can be fixed by putting something in the registry. The URL To that is here: http://www.amd.com/products/cpg/athlon-duron/largePageMinimum.reg
Hope this helps.