On my first build, I used the HDD from my HP pavillion 7955; trouble is HP put some sort of 'tatoo' on the HDD so it would only let you get into it if it was hooked up to the exact same motherboard make&model... simple fix was to buy XP home upgrade version and do a repair install.
On my second build currently, i wanna use the same HDD, but when booting up it only gets to that windows XP start-up screen and reboots continually... when I put in the XP upgrade and press 'R' for repair install, it goes to this Recovery console, asks me what windows installation I want to log into ,then asks for an administrator password?
I never created any seperate administrator/user/guest accounts on XP, let alone any passwords.
The onset of having to buy XP again and a new hard drive is very depressing