Microsoft will today release a new version of its flagship Windows operating system tailored for a world shifting from personal computers to smartphones and tablets.
The software giant gambled by changing long-familiar user interface features to make Windows 8 compatible with the trends of keeping programmes and data in the internet "cloud" and relying on mobile gadgets at work and at home.
"Microsoft has this vision where they want to go; and it is Windows in the cloud," analyst Michael Cherry of Directions on Microsoft said. "The chasm is very big and Windows 8 is a good first step … But, all of these transitions come with a little pain."
The arrival of Windows 8 will coincide with the availability of Microsoft Slate tablet computers to challenge Apple's market-ruling iPads and rivals built on Google's Android software.
Slate tablets will be among Windows 8-powered devices sold in real-world Microsoft stores that will "pop up" today in the United States and Canada.
Microsoft promised that the temporary, holiday-season shops will feature a "curated collection of Microsoft's coolest products".
Windows 8 and an accompanying version of Microsoft's free Internet Explorer web browsing programme, were designed to make the most of touch-screen capabilities.
"This is an absolutely critical product," Microsoft chairman Bill Gates said.
"It takes Windows into the world of touch, low-powered devices, really giving people the best of what we think of as a tablet-type experience and the PC experience … It is a big step."
Windows 8 will support various devices, including touch- and stylus-based smartphones and tablet PCs as well as desktop and laptop machines. Versions of the operating system have been tailored for chips used to power various mobile devices.
The fate of Slate and other Windows 8 tablets will likely hinge on the availability and pricing of applications, since fun or functional "apps" are what people tend to love about gadgets, according to Cherry.
"Frankly, even an iPad out of the box isn't really exciting; it is a platform things can run on," he said. "The real question is how many apps really exploit the Windows 8 platform, and right now the number of apps you can truly get excited about is quite low."
Microsoft would "get software developers behind this", Gates added.
Apple on Tuesday introduced a fourth-generation iPad and a "mini" version of its hot-selling tablet computer while touting the fact there are more than 275,000 "apps" for the tablets.