Microsoft has finally launched its latest operating system, Windows Vista some 2 years behind schedule.

At a press conference at NASDAQ MarketSite in Times Square, Microsoft's Chief Executive Officer Steve Ballmer announced the business availability of the Windows Vista operating system, as well as the 2007 release of Microsoft Office.

However consumers will have to wait another 2 months before Microsoft releases a consumer friendly version of the software.

“These are game-changing products”, Ballmer said. “It’s an incredible step forward for business computing in a year of unprecedented innovation from Microsoft. We expect that more than 200 million people will be using at least one of these products by the end of 2007.”

The development of Office and Vista took 5 years and $20bn (£10bn), managing director of Microsoft UK, Gordon Frazer told journalists at the product launch in London.

While the launch is expected to be the most successful operating system launch for the company, many computer makers are quietly complaining that they won't be able to install the consumer version on PCs to sell in the run up to Christmas.