Microsoft said more than 240 million Windows 7 licenses have been sold during the first year of the operating system's availability, a record the company says makes it the fastest selling OS in history.

Microsoft says in a blog post that six months after Windows 7's launch, all 18,000-plus of its OEM partners were selling Windows 7 PCs whereas only 70% did so for Windows Vista in the first six months after it launched. And OEMs have basked in the glow of positive Windows 7 reviews, scoring higher on customer satisfaction surveys themselves. 

In July, Windows 7 passed Windows Vista in global usage share and now has roughly a 17% share (Windows XP still leads the way), according to market watcher Net Applications

More than 10% of enterprises have completed Windows 7 migrations, and most others will at least start the process this year or next, according to a September 30 poll of 115 IT decision makers who are clients of analyst firm Directions on Microsoft.  Early adopters of Windows 7 say that using virtualisation technology is key to making a smooth transition. 

Microsoft has offered an ROI calculator to entice potential Windows 7 shops with potentially big savings. Meanwhile, job opportunities could open up for those with Windows 7 migration expertise. 

Windows 7 has also been embraced by developers. In a survey of 606 respondents conducted in May, Embarcadero found 54% were developing apps for Windows 7 and another 25% planned to do so within the next year. Gartner also warned attendees at its Symposium/ITExpo event this week to get moving away from Windows XP, as application developers will increasingly ignore it when rolling out new apps. 

Windows 7 isn't just for PCs either. The OS is finding its way into a slew of tablets ready to take on the Apple iPad. 

All this isn't to say Windows 7's ride has been entirely smooth. Like its predecessors, Windows 7 has started to show up regularly in Microsoft's monthly Patch Tuesday list of software fixes.