Europe is getting an extra version of Windows Vista today in order to comply with the EC's anti-trust ruling.

Microsoft officially releases the operating system to business today but it was back in 2004 that the Commission ordered the software giant to release additional versions of Windows that come without its Windows Media Player software. The idea was to prevent Microsoft's dominance in the desktop OS market from giving it an unfair advantage over rivals RealNetworks and Apple, among others.

That resulted in versions of Windows XP called "Edition N" which sold for the same price as the standard Windows XP. With the release of Windows Vista, Microsoft is having to do the same again.

The company was still working with the Commission to determine exactly how many N versions are required, but it expects to offer them for both home and business users, said a Microsoft spokesman. "To comply with the ruling, Microsoft will have to produce an Edition N for all future editions of Windows," he confirmed.

Microsoft released Windows Vista Business and Windows Vista Enterprise to its volume licensing customers today, along with Exchange Server 2007, its email server product, and the Office 2007 productivity suite; the UK launch was held at the Emirates Stadium in London. Consumer editions of Vista are due for release on 30 January.

The main additions to Vista are better security, a revamped user interface called Aero and, for businesses, features to help to reduce PC management costs.

Critics have noted that there has been little support from PC makers for the "N" versions of Windows, undermining the effectiveness of the Commission's ruling. Most PC makers chose not to offer Windows XP PCs with Edition N, citing little interest from customers and the expense of supporting extra versions of the OS.

The anti-trust ruling also ordered Microsoft to release protocols used by its work group servers to allow competing software to operate more smoothly with Windows. It isn't launching the server version of Vista, codenamed Longhorn, until late 2007, so the company doesn't have to submit the protocol information for it yet.

"Documentation for Vista work group server products would be needed when they do launch a Vista server system, but we don’t require documentation from the Vista PC OS," Microsoft said.