According to the article, Microsoft's requirement is that Vista be installed over a pre-existing XP installation, invalidating the old XP license in the process."Just when everyone thought that all hope was lost when it comes to performing a clean install with a Windows Vista Upgrade DVD, a gleam of light can now be seen at the end of the tunnel. A new workaround proposed by Paul Thurrott (via Microsoft internal documents) has been confirmed to work by DailyTech.
AlHunt writes "Daltytech.com is reporting a workaround to do a fresh install of Vista from your Upgrade DVD, based on an internal document from Microsoft. From TFA: