Microsoft's Windows of opportunity?

Microsoft introduced the biggest overhaul of its flagship Windows software in two decades, reflecting the rising stakes in its competition with Apple and Google for customers who are shunning personal computers and flocking to mobile devices.

"This is the biggest product we've ever done," chief executive Steve Ballmer said, comparing it with the PC's arrival in 1981 and the introduction of Windows 95.

Microsoft packed the new Windows with touch-screen capabilities, designed to vault the company into the tablet market dominated by Apple's iPad. To avoid being left behind as computing shifts to mobile devices like tablets and smartphones, the company radically altered Windows' familiar design and scrapped a strategy that had it relying entirely on partners to produce Windows computers.

"In creating Windows 8, we shunned the incremental," Windows president Steven Sinofsky said. Windows 8 and the company's first computer, the Surface tablet, went on sale yesterday.

More than 1,000 computers had been certified for Windows 8, Sinofsky said. That includes the first Windows machines capable of running on chips with technology from ARM, instead of Intel. Besides Microsoft's own Surface, the list of ARM-powered machines includes computers from Dell, Samsung Electronics, Lenovo and Asustek Computer. These run a version called Windows RT.

Still, Surface and the other Windows RT machines will be constrained in competition with Apple because they do not work with some of the most widely used downloadable applications. The RT-based machines can only run apps from Microsoft's new Windows store, which will not feature applications for Facebook or Apple's iTunes.

The Windows store does have some popular apps, including those from media-streaming companies. Still, Microsoft will not say how many apps are available, and the lack of a broad range of games, tools and other downloadable software will detract from the Surface in a head-to-head comparison with the iPad and its 275,000 apps.