Microsoft's first major upgrade of its operating system in five years is complete and will be available to retail customers on January 30th, the company has indicated.

Plagued by a series of development delays, Windows Vista is front and centre of a new product cycle at the world's largest software maker that includes a new version of its Office business software suite.

Jim Allchin, co-president of Microsoft's platforms and services division, said it expected consumers to make a "fast and immediate" switch to the new Windows.

"On January 30th, you will be hard pressed to find a machine that doesn't have Windows Vista available," said Mr Allchin in a conference call with reporters and analysts.

In the first year of release, Vista will be installed on more than 100 million computers worldwide, according to research firm IDC. Windows already sits on more than 90 per cent of the world's computers. Microsoft originally targeted a 2005 launch for Vista, then pushed the release out to 2006 before announcing in March that Vista would again be delayed.

There was also speculation among analysts that Microsoft would have a hard time meeting its early 2007 target.

Meanwhile in the clearest signal yet that Microsoft and the European Union have established their own entente cordiale, Microsoft founder and chairman Bill Gates shared a stage in Brussels yesterday with Matti Vanhanen, the Finnish prime minister and current president of the EU Council, to discuss innovation in Europe.

In 2004, the European Commission hit Microsoft with a fine of €497 million for what it saw as abuse of its monopoly in the PC market. Last month Microsoft said it had made changes to the forthcoming Vista version of the Windows operating system that it believed would make it compliant with EU competition law, while it continues to appeal the record fine.

Speaking at a Microsoft-organised event devoted to innovation in Europe, Mr Gates and Mr Vanhanen took the opportunity to give their views on key aspects of European technology policy.

"The incentive systems around copyright and patents . . . have been, along with the universities, the thing that has allowed the US to really be very strong," said Mr Gates.

"If you invent a new approach in software, you should have a patent right in that."

Although the issue of harmonising patent policy across Europe and whether or not software should be patentable, as it is in the US, were discussed at an EU summit last month, Taoiseach Bertie Ahern said then that EU leaders were no closer to agreement on the issue. Additional reporting by Reuters