Microsoft CFO Peter Klein said Microsoft has sold 90 million copies of Windows 7 since its introduction on October 22, 2009. At the Morgan Stanley Technology, Media & Telecom Conference in San Francisco, he added, “We see continuing momentum in Windows 7 to date.” [InformationWeek]

Selling 90 million copies in about four months makes it the fastest selling operating system in Microsoft’s history, Klein added. The company also expects the demand to go up significantly because of a product refresh coming from enterprise customers as they upgrade their systems from XP to Windows 7 in mass in 2010 and 2011.

And of course, Microsoft credited its hardware partners, Dell, Sony and HP, for releasing innovative devices that run Windows 7 to attract consumers to purchase more.