My systems are all rather old -- running Pentium 4 CPU's in 478 pin sockets. From the time I built them, they have run Windows XP (now with SP3 installed) on IDE drives. Rock solid and stable. Two are on ABIT IS7 -- one a V2 and one an E -- motherboards and two are on ABIT IC7 G motherboards. Recently with the dramatic price drops on SATA drives I bought two of the Western Digital black 640 GB drives planning to make them the C drives in the two machines I use most to get a boost in speed. I had no trouble installing Windows XP to the WD drive and the speed improvement as measured by HDTach is very impressive. So long as the only drive connected is the SATA drive the system(s) boot and run perfectly. I had planned to reformat the old 500 GB Seagate IDE drives that used to be C drives and use them for file storage. If I connect an IDE drive to either of the IDE connectors on the motherboard where the SATA drive is set to be the boot drive, bootup fails with an error message saying no OS was found etc. I have read the manuals carefully and can't find any information on getting SATA and IDE drives to play nice together. I had assumed there was some place in BIOS to do this -- but so far as I can tell, there isn't. There doesn't appear to be a place in the BIOS to set boot to be SATA instead of IDE, and it is clearly defaulting to the IDE drive if an IDE drive is present. I could just buy another WD SATA drive, but I have all of these Seagate 500 GB drives that would make superb archive drives. Seems a shame to not use them -- if only I can figure out how to do that. Any help or suggestions would be appreciated.