Microsoft officially said there will be six versions of Windows Vista. Here's a list:
Vista Business - for companies of all size, with tools to help organizations manage their PCs.
Vista Enterprise - has all features of the basis version plus improved encryption and a BitLocker system to prevent confidential data from being viewed if a computer is lost or stolen.
Vista Home Basic - the basic version for home users with desktop search and security tools.
Vista Home Premium - has all features of the basic version and features the new Areo graphics interface and Xbox 360 connectivity too.
Vista Ultimate - a version that combines the features of the business and home editions in one package.
Vista Starter - a streamlined version for cheap low-power computers found in many developing nations.
Additionnally, there will also be versions for the EU without Windows Media Player.