Microsoft has announced that more than 20 million copies of Windows Vista were sold in the month after the new OS was released worldwide on January 30.
That means Vista is selling at more than twice the rate of its predecessor - it took Windows XP two months to achieve sales of 17 million.
The 20 million figure is comprised of Windows Vista licenses sold to PC manufacturers, copies of upgrades and the full packaged product sold to retailers, and upgrades ordered through the Windows Vista Express programme between January 30 and February 28.
"We are encouraged to see such a positive consumer response to Windows Vista right out of the gate," said Bill Veghte, corporate vice president of the Windows business group at Microsoft.
"While itâs very early in the product lifecycle, we are setting a foundation for Windows Vista to become the fastest-adopted version of Windows ever."
Vista was launched in the UK with a special event at the British Library, where Bill Gates discussed some of the operating system's new functionalities.
There was little mention of gaming at the event, but since then Microsoft has revealed more details of Games for Windows Live, which will allow PC and Xbox owners to compete against each other in multiplayer games.