There is a workaround for the silly way in which Vista checks to make sure that you are actually upgrading a previous version of Windows. I wrote about this previously, where I actually had to install Windows XP to use the 32 bit upgrade of Windows Vista after I had “mistakenly” formated over my XP installation to install a clean copy of Windows Vista.
There is a way around this that I mentioned in the previous article though.
Install Windows Vista 32 bit on a clean partition using the partition tools, but do not enter in a license key. Once Vista is completely installed you can boot into it for the first time. At this step you will figure out that even when entering in a valid key (although for an upgrade), you will be unable to actually use it because Vista still demands that it be upgraded from a previous version and not a clean install. To get around this, just install Vista on top of itself as an upgrade which circumvents the whole purpose of this silly routine … making sure you have Windows XP or Windows 2000. When you upgrade your unlicensed version of Windows Vista 32 bit you will have no ill effects, a “semi” clean install, and a useless “Windows.old” directory that you can just delete. With this method you do not have to touch your XP disk, although you will have to install Vista twice. What a pain.