In what the company claims is its biggest release since Windows 95, Microsoft has kicked off the day-long launch of its Vista operating system, Office 2007 suite and Exchange Server 2007.

Two launch events have already been held in Asia, and another in Australia, with Vista and Office 2007 available to volume licensing customers now and Exchange Server 2007 appearing in mid-December.

It's the first time that new versions of Windows and Office have been launched simultaneously since 1995 and that makes it one of most important days in Microsoft's history.

"I'm super excited about this launch today. It's been a very long journey but now I can say that we have truly arrived," said Darren Huston, president and chief executive officer of Microsoft's Japan unit.

The launch, which began with an event in Sydney and was followed with similar events in Tokyo and Beijing, provided Microsoft a stage from which to talk up the three products and showcase some of the businesses that have already committed to roll-outs.

Microsoft Japan has 57 companies that have said they'll roll-out at least one of the three products. The list includes Sharp, Sanyo, McDonalds and Nikon.

Speaking in Tokyo, Jay Jamison, leader of Microsoft's Windows business group in Japan, said, "We are hopeful and optimistic that in Japan Windows Vista will be the most successful business OS release of Windows ever."

In Australia, companies including BDO Chartered Accountants & Advisers and alcoholic drinks company Lion Nathan have begun testing the products.

Later today Microsoft will hold launch events in London, Munich, Paris, Toronto and New York. A consumer version of Windows Vista is due on January 30.