My question comes when you cannot do an upgrade from Vista Home Premium to Win 7 Professional. You have to do a custom install, which might mean wiping the drive first.
I got the following response from Microsoft, and I think I understand, but if anyone would like to say it in plain language, please do so.
[FONT="]"I appreciate the opportunity to assist you today, I understand that you would like to know that if you use the upgrade version of Windows 7 if it will render the Windows Vista you currently have installed un-useable.[/FONT]
[FONT="]Should you chose to use an upgrade version of Windows 7 over a copy of Windows Vista it will lock the previous copy of Vista un-useable as long as you use the upgrade version on that computer. If you wish to re-use your copy of Windows Vista you would have to purchase the full version of the product and perform a clean installation of Windows 7. Doing this allows the Vista to be uses for another PC in your household."[/FONT]