Hi 86, I bought the Windows 7 operating system outright, not on a PC. I had to as I was doing a clean install on this newly built PC. I previously bought the XP Pro operating system outright as well. After a new install one often has to call Microsoft to verify the install if it won't register after installation.
I used the XP Pro disc at least a dozen times on PC's after crashes and re installs...Microsoft have always been obliging in my experience...