Microsoft has moved to re-assure European regulators there's nothing anti-competitive going on with its delayed Windows Vista operating system.

The company told the European Commission Wednesday it's working hard with partners and competitors to build products and services capable of working with Windows Vista.

Microsoft said it was a "priority" to keep outsiders informed about product plans. "We have worked hard to include partners and competitors in our planning so they can build products and services that work with Windows Vista," Microsoft said. Microsoft was responding after it emerged European competition commissioner Neelie Kroes has taken what could turn into the first steps in an official investigation into Windows Vista.

Kroes is reported to have written to Microsoft's chief executive Steve Ballmer expressing worries about Windows Vista's bundling of features. Concerns specifically appear to center on packaging of internet search functions and software, and the ability to create fixed document formats.

Kroes told the Wall St Journal Europe he expects Microsoft will design Windows Vista "in a way which is in line with European competition laws." "It would be rather stupid to design something that is not," Kroes said.

The warning comes as Microsoft prepares for two days of hearings into whether it should pay a 200-million-a-day euro fine for allegedly failing to comply with the terms of a 2004 EC ruling that found Microsoft had hurt the competition in low-end servers and media players through its established practice of bundling software.

Microsoft does at least appear to have taken some steps to satisfy regulators in Windows Vista. The company plans SKUs of the home and business edition without the Media Player, which helped originally land the company in hot water with Europe's competition chiefs.

As is Microsoft's way, though, the latest planned version of its operating system promises integration in other areas that were bound to concern regulators. Aside from search and document formats, there is also tighter integration at an architectural level with Office.

Pressure, or even a probe, from Europe is unlikely to get in the way of Microsoft's already delayed development and delivery plans for Windows Vista. Microsoft pressed on with Windows XP in 2001 despite the fact its long-running case with the US Department of Justice hadn't wrapped-up.®