Microsoft's Windows Vista OS has sidestepped antitrust concerns, according to the latest status report on Microsoft's compliance with the US antitrust settlement.

Microsoft has increased its cooperation with the court's technical committee in several ways to help ensure that middleware vendors have their software ready for Vista before the OS ships, the report said. The company has also addressed all of the bugs identified relating to how third-party middleware software interacts with Vista.

The document defines middleware as software programs such as instant-messaging tools, media players, email clients and internet browsers. Around 30 vendors are working with regulators and Microsoft on the way their software works with Vista, the report said.

The US government and states that were a party to the antitrust suit against Microsoft have conducted "extensive testing" of interim builds of Vista and Internet Explorer 7.0 to ensure compliance with the November 2002 antitrust settlement.

As part of that settlement, Microsoft agreed to license communication protocols to IT vendors interested in developing server software that works smoothly with its Windows operating system.

After complaints, Microsoft is rewriting some of the technical documentation for its MCPP (Microsoft Communications Protocol Program).

The status report said Microsoft has made the new documentation easier to understand, but the company needs to stay on schedule for delivering further documents. Microsoft has until November 2009 to provide the information.

The European Commission has also been scrutinising Vista, following its 2004 antitrust ruling against Microsoft. So far, the Commission has taken no action against Vista. Microsoft has warned that if regulatory interference delays Vista's European launch, it could hurt Europe's economy.

Microsoft plans to release Vista to business customers on 30 November.

In 2004, the Commission fined Microsoft for abusing its monopoly in the desktop OS market, ordered it to release a version of Windows XP without Windows Media Player software, and mandated it to license and document protocols used by its server products. Microsoft is appealing the decision before the European Court of First Instance in Luxembourg.