didn't say how it came to that number, only citing both internal and external checks. But the number jibes with that of Web metrics vendor NetApplications, which measures operating system usage share by tracking a pool of some 160 million monthly unique visitors to the sites it monitors. According to NetApplications, Windows 7 accounted for by the end of March.

"It's simply difficult to get around Microsoft," observed Krans, who wasn't surprised by the year-over-year jump in Windows 7 sales to consumers. Rather than attribute that licensing increase to Windows 7's quality -- which has received mostly positive reviews -- he said it was directly tied to the upswing in PC sales.

"Its performance was largely driven by the underlying PC market," Krans argued. Although both consumers and businesses may have postponed buying new PCs during much of Vista's reign, they appear to be back in the buying mode. PC purchases were up an industry-wide 25%, Microsoft said, with consumer PC sales up 30% and business PC buying up 14%. Microsoft used the estimates to boast that increases in Windows license sales exceeded both those numbers.

"The wave of technology refreshing is lifting Microsoft's boat, along with the PC OEMs," said Krans.

Krans' point has been reinforced by data from NetApplications. Since Windows 7's release in October, Windows XP has lost more than twice as much share to Windows 7 than has Vista, illustrating that XP users who held onto their old PCs were especially eager to buy new machines.