My Western Digital came with a floppy to switch to ata66, which I had to do to get win2k to install/run correctly. It does say that it's only for wd drives though, but I am willing to email the file to you if you want to try it. What mb are you using? Have you updated the bios and drivers? I've heard of people successfully using ata100 with win2k, although there isn't much of a performance increase as todays drive max out at around 37mb/s sustained read. The only benefit of ata100 over ata66 would be in burst transfers.