Bill Gates will have clocked up a fair few airmiles once his Windows Vista launch tour is over. Starting in New York last night, he then officially unveiled his new operating system at the British Library in London this morning.

After some 20 minutes of speaking in London, he was off again, to Edinburgh, to join the Microsoft Government Leaders' Forum .

Windows Vista went on sale in 70 countries today, along with the new Microsoft Office 2007 suite, and a new version of the Microsoft Exchange e-mail software.

Stores across the world were opened before dawn - some throughout the night - as part of the launch, but there was no major rush as with the recent Nintendo Wii or Sony PlayStation 3 launches.

Global launches

In New York last night, Windows fans gathered in Times Square for the official launch. Despite freezing temperatures, people queued up to ensure they could get their hands on a copy of Windows Vista before anyone else. Flags forming the red, green, blue and yellow Windows logo were hung from surrounding walls.

In London, some 30 people waited outside the PC World store on Tottenham Court Road when it opened its doors at 6am this morning. The store had been kitted out with Vista displays and computers with the operating system pre-installed.

Vista first went on sale in New Zealand, due to its geographical location, and Japan was next.

In Tokyo last night, hundreds of people queued up at various electronics stores in the Akihabara district to become among the world's first consumers to own Windows Vista. A large-screen TV displayed a countdown to the midnight launch.

Vista available for download

At the US launch, Microsoft CEO Steve Ballmer said that despite consumers being able to download Windows Vista over the internet for the first time, most consumers will upgrade only when they buy new computers.

The long-awaited Windows Vista is the first major release of a new Microsoft operating system since it introduced Windows XP in 2001. Microsoft called Windows Vista the "most important release of its dominant operating system since Windows 95" more than a decade ago.

In the UK, Windows Vista costs between £100 and £370 depending on which version is chosen.