ATA-100 on MB and Windows 2000

i have an Asus A7v motherboard, it support for 4 standard IDE devices and 4 ata-100 devices.
I;ve got 98SE installed and it worked fine, for experimentation(college) i added 2 installs of Win2000 server to the drive all OS have their own partition on physical drive. now i cannot get anything to boot. blue screen stop errors. ideas wanted.