I have a HP Pavilion a250n with a bad motherboard and a good 120GB hard drive with the xp os still installed along with the rest of the factory installed softward. I also have a HP Pavilion a510n which also has a 120GB hard drive that lost all software and the repair shop installed new xp home only, no other software. I tried to switch the two hard drives since the a250n worked fine. I got the message about a configuration error and code purple. I talked to HP Support via email, and they said it was because each computer has its own tatoo on the motherboard and I would have to reformat hard drive and then use the system restore disks or if I didn't have system restore disks, I could purchase them from HP website if they were still available. If not, I would have to have an authorized HP shop install Win XP all over.