Microsoft Corp. on Thursday said it had sold its 60 millionth copy of Windows Vista operating system (OS) late in June, dispelling concerns about slow adoption rate of the new OS that has been in development for more than five years. In addition, the world’s largest software maker’s chief executive said that in a year time there will be more Windows-based computers than there are cars.

“So really if you do over the last six months since our consumer launch, 60 million units have been sold of Windows Vista into the marketplace,” said Kevin Turner, chief operating officer at Microsoft.

Back in mid-May Microsoft indicated that it had managed to sell 40 million copies of Microsoft Windows Vista OS in the first 100 days after the company released its long-awaited software for consumers. The company even boasted that it managed to leave the whole install base of Apple’s Mac OS in weeks.

“By our math1 we eclipse the entire install base of Apple in the first five weeks that this product shipped,” Mr. Turner added.

But even though Windows Vista has been gaining popularity among consumers and enterprises in the recent months, it still has negligible install base among all computers running Microsoft Windows operating systems. According to the head of Microsoft, by mid-2008 there will be about 1 billion computers running a form of Windows OS.

“The install base of Windows computers this coming 12 months will reach 1 billion. If you stop and just think about that, parse that for a second, by the end of our fiscal year ‘08, there will be more PCs running Windows in the world than there are automobiles, which is at least to me kind of a mind-numbing concept,” said Steve Ballmer, chief executive of Microsoft.