How can I install Windows Vista upgrade on a machine that has no OS?

A. Vista's price structure makes it far more attractive to purchase the upgrade version rather than the full version. Obviously, there are license implications, but if you prefer a clean installation and don't have your Windows XP media, Vista can be upgraded without a previous installed OS but it isn't a pleasant procedure, and you basically have to install Vista twice. To perform the upgrade, follow these steps:

  1. Boot from the Vista Upgrade DVD and start the setup program.
  2. When prompted to enter your product key, don't enter one. Instead, click Next and proceed with the setup. This will install Vista as a 30-day trial.
  3. When prompted, select the edition of Vista that you purchased and continue with setup.
  4. Once the setup process is complete and you've been brought to the desktop for the first time, run the installation program from within Vista. This time, enter your product key when prompted.
  5. When asked whether to perform an Upgrade or Custom (advanced) installation, choose Custom (advanced) to perform a clean installation of Vista. At this point, you're installing Vista again
  6. Once setup has completed for the second time, you should be able to activate Vista normally. You can also delete the Windows.old directory, which contains information from the first Vista installation as the figure shows. This Windows.old directory contains the Program Files, Users, and Windows content from the previous operating installation but not any other folders. If you upgrade multiple times, the previous Windows content will be saved as Windows.old.000, Windows.old.001, and so forth.