New Parallels and a MAC so I need some help. In a PC if I needed to uninstall windows I reformatted. With my system I do not know what to do The situation: I installed Parallels on a MAC followed by Windows 7. On registering Windows I discovered it was an upgrade and not a new install. So I have to uninstall W7, install my XP version and then reinstall W7. How do I do this?