You can install the upgrade version of Vista even if you don’t have XP or 2000 installed, or even without access to a disc with one of the old OSes.


Link:
http://…/whoops-you-can-install-the-vista-upgrade-without-xp

Check out these posts too:

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  3. Safely install software in a virtual layer – Lifehacker
  4. How to get Vista fonts in XP
  5. Windows 7 Upgrade Advisor
  6. Should I Upgrade to Office 2010?
  7. Vista Web Buttons