So I'm still dealing with this problem.... I've got my system running XPpro on a 20GB PATA with an extra 20GB PATA for storage, had it this way for a long time now. Now after I purchase a WD 250GB SATA drive to throw in there for additional storage, it doesn't show up at all in Windows Explorer or Drive Manager. BUT it does show up fine in the BIOS. I've already formated to NTFS and partitioned it using XPs DOS setup CD. My system is loaded with SP2 and all the SATA drivers so there should be no reason for the SATA not to show up in Explorer. So my question is.... In a system that uses both SATA and PATA hard drives, does the operating system have to run off the SATA in order for all drives to be present???