Maybe I don't understand proper English, However, UPGRADE means you would be
upgrading from a previous verison of Windows - 95, 98, 98SE 2000, Me, XP
etc. If you were to Reformat your hard drive and tried to upgrade, you would
be told no OS dected, and would not be able to go any further.
You can do a full install with an existing OS already on the HD, all your
data would be lost. You can also reformat the HD then do a full install.