Upgrade Planning for Windows Vista
Your upgrade options are dependent on the version of Windows that is currently running on your PC. You can upgrade from your current edition of Microsoft Windows XP or Windows 2000 to a corresponding or better edition of Windows Vista by purchasing and installing an upgrade copy of Windows Vista. For more information related to the upgrade chart try @ https://www.microsoft.com/windowsvista/getready/upgradeinfo.mspx
The table below outlines the upgrade options mapped to the different Windows Vista ditions.
Requires clean install.
In-place installation option available.