I have tried multiple configurations with my Promise Ultra ATA 66 card. I have 2 Ultra 66 HD's, configured as primary & slave. I have tried having them on the same ribbon (Ultra 66 ribbon, of course), and on separate IDE channels on the Promise card. When in Windows 98 (2nd edition), the HD's seem to pause the whole computer system when transferring files. The only kind of pause I can compare it to is using a parallel port scanner, when everything seems to freeze for a couple seconds while scanning. Any advice would be appreciated...