Is this legal?
One might naturally wonder whether the aforementioned instructions describe an action that is legal or ethical. After all, anyone could purchase an Upgrade version of Windows Vista (therefore saving a lot of money when compared to a Full version) and use it to perform a clean install even if they don't own a previous, compliant Window version.
After telling my "Windows Vista Secrets" coauthor Brian Livingston about this workaround, he wrote that using this process was indeed ethical, in his opinion. "Microsoft itself created the upgrade process," he wrote in a newsletter article describing the workaround. "The company designed Vista to support upgrading it over a previously installed copy of XP, W2K Pro, or Vista itself. This isn't a black-hat hacker exploit. It's something that's been deliberately programmed into the approved setup routine."
Fair enough. Of course, if you do use this workaround to clean install Vista with the Upgrade media, and you don't own a previous, compliant version of Windows, you're most certainly violating the Windows EULA and, thus, breaking the law. Proceed at your own risk.