If you plan to buy Starter, Home Basic and Home Premium editions (32-bit and 64-bit included) of Windows Vista as upgrade version for your Windows XP or Windows 2000 machine to take advantage of cheaper price of Windows Vista upgrade license or product key, you may want to think twice and consider carefully. Although the price of upgrade version of Windows Vista operating system DVD license can be lower by up to 33-50%, but unlike Windows XP upgrade CD or upgrade key, Windows Vista upgrade DVD cannot be used to perform clean or fresh installation of Windows Vista on your computer, new or existing.

Microsoft says that Windows Vista does not let you perform a clean installation by using the upgrade key even though you have purchase an upgrade key for Windows Vista to upgrade your Windows XP or Windows 2000 system, and thus you cannot upgrade to Windows Vista without earlier version of Windows operating system installed. This cause of the problem is because Windows Vista does not check upgrade compliance. When upgrading to Windows XP by using upgrade version CD, installation process will ask user to insert CD of previous version of Windows for verification that the user actually owns the it. Therefore, you cannot use an upgrade key to perform a clean installation of Windows Vista.

The workaround or solution for unable to upgrade to Windows Vista with upgrade DVD media requires you to first install earlier and support version of Windows operating system on the computer, and then perform the upgrade to Windows Vista. This will mean there won’t be clean install of Windows Vista. You may however, perform clean install of previous version of Windows to ensure that the upgrade to Windows Vista is on clean state of Windows XP or 2000.

Other resolution is to purchase a license that lets you perform a clean installation of Windows Vista, which is full version and product key of Windows Vista, at no discount price. However, if you already purchased the upgrade version, you may have to live with the steps to install old Windows first, unless you can return the Windows Vista retail package for exchange.

Check out also limitations on ability to in-place upgrade to Windows Vista, if you intend to purchase upgrade edition of Vista DVD license and product key.

Update: There is 2 hacks evolved that allows user to clean install Windows Vista with just upgrade DVD, or simply use the Windows Vista upgrade version product key to activate fresh copy of Vista.