I am currently running Windows XP, it was installed on the C drive and the XP disc back up was saved on a different partition. That partition has since been lost, so although I still have the CD key, I have no way of re-installing XP. If I bought the Windows 7 home upgrade, would I have any way of re-installing it if my hard drive was damaged. Would the Windows 7 upgrade require installing XP before I could install it?