According to website ActiveWin, via Engadget, there are six core versions of Microsoft Vista to choose from, plus two European-only versions without Windows Media Player, designed to comply with antitrust rulings.

They are:
– Windows Starter 2007 – barebones version of Vista without the Aero interface
– Windows Vista Home Basic – similar to the existing XP home (Windows Vista Home  Basic N is the EU-compliant version)
– Windows Vista Home Premium - includes Media Center functionality and Cable Card support
– Windows Vista Business – the successor to XP Professional.( Windows Vista Business N is the European version)
– Windows Vista Enterprise – designed for the enterprise sector, an includes features such as Virtual PC and volume encryption.
– Windows Vista Ultimate – Vista with all the bells and whistles.