Vista upgraders will no longer be able to do a completely clean install.
End users buying upgrade versions of Windows Vista will no longer be able to use the disc to install a clean version of the operating system.
This news has broken a long-standing tradition, where the upgrader could simply go through the normal setup routine and insert a previous version of Windows
Instead, Microsoft now requires end users to have a genuine Windows installation before allowing an upgrade to Vista
from inside the activated copy of Windows XP or Windows 2000.
Of course, this won't be a problem for most users, because they're more than likely to have a previous copy of Windows installed. However, for the enthusiast market, it could pose some problems.
Those looking to save a dime or two by buying the upgrade version will not be able to do a clean installation of Windows Vista. If the hassle of installing and activating a previous version of Windows is too much, you're going to have to save up for a full version of the OS.
Did you used to clean install with an upgrade CD? Let us know in the forums