Microsoft CEO Steve Ballmer described Windows 7's first ten days of sales as "fantastic" while in Japan yesterday. And while he didn't provide specific numbers, he did add that the first 10 days of Windows 7 sales generated more revenue than had any previous Windows version in the same time period.

Windows 7's torrid sales pace actually started well before the system became generally available, on October 22. In the previous quarter, Microsoft sold more copies of Windows than it had in any quarter in its history. Much of that was from Windows 7 pre-orders, though the company actually deferred reporting half of those sales for the current quarter.

Roughly 95 percent of Microsoft's customers acquire Windows with a new PC, and Windows 7 is expected to lead a tech industry rebound in coming quarters. "People don't buy operating systems, they buy computers with operating systems on them," Ballmer noted, saying he is now "more bullish" on the PC market than he's been in many months.

Related Reading: