Change the hdd type from sata to ide. Change the hdd type from sata to ide. The only way to install XP over Vista is to first format the hard drive, thus removing all traces of Vista and clearing the HDD of any information that may cause a conflict. Once formatted, XP SHOULD install as it would on any new system. Alternatively, buy an Apple Mac and save yourself the trouble of continually upgrading a windows based PC just to line the pockets of Microsoft :)