Microsoft has taken a wiser approach to licensing in Windows Vista in an attempt to curb one of the most wide-spread piracy methods for Windows XP - Volume Licensing abuse.
Windows XP Professional (available on Volume Licensing) was a superset of the features found in Windows XP Home Edition, so System Builders and OEMs could ship their PCs with a copy of Windows XP Professional and use an illegally obtained Volume License Key (VLK).
However, with Windows Vista, only Windows Vista Business & Enterprise will be available on Volume Licensing, which do not contain much of the functionality found in the Home and Ultimate editions, such as Windows Media Center, support for Media Center Extenders, Windows Movie Maker, Windows DVD maker, Windows Ultimate Extras etc. This significantly reduces the issue of System Integrators and OEMs illegally using Volume Licensing Keys (VLKs) to install Windows on their PCs and sell to home users.
Windows Ultimate Extras is unlikely to be available to users who obtain Windows Vista through testing and development channels, such as Microsoft Developer Network (MSDN) subscriptions and TechNet subscriptions, reducing the likelihood of misuse of development-only licensing.
Licensing, Piracy, OEMs