*If I'm wrong, pleaes correct me* isn't XP home like XP PRO, doen't have a upgrade version and full install version? aren't they together? If not, then i'm wrong. If you want to buy a upgrade version of XP home, you don't need to reformat you hard drive, in fact, if you format you hard drive, you won't be able to install a upgrade version, you just start windows ME, pop in the CD, follow the wizard, then your computer well be running as XP home in about 30 minute:D