If the MB supports ATA 100 and you have it setup for it with the proper cable, it should be fine. Some of the MB's have to be set in bio's for the ATA 100, some only support ATA 66. My son's MB supports ATA 66 in the documentation, but it had a flyer added that says the manual is wrong and it will work at ATA 100. Seems to be fast enough (its a 7200 rpm Maxtor). Another board I had needed Window ME to install the driver to run at ATA 100. Its brand new and still in the box. I may find another slot 1 cpu and put it together, but it will be a pain until I get Win ME to make it work.
B Earp