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After 1.2 billion hours of user testing, Windows 8 is good to go

"In the case of Windows 8, seeing, touching, clicking and swiping is really believing," said CEO Steve Ballmer. Now Windows users will have a chance to decide for themselves whether Windows 8 is a hit or miss.

Steven Sinofsky introduces Windows 8
Sara Tew/CNET

After several years of development, now it's your turn to vote for or against Windows 8 with your wallet. Windows 8 goes on sale around the world at 12:01 a.m. local time, with an upgrade price as low as $39.95.

"This is the best release of Windows ever," Microsoft Windows chief Steven Sinofsky said at the Windows 8 launch event in New York today. He noted that Windows 8 has been heavily road-tested, with 1.24 billion hours of pre-release testing across 190 countries.

Read: Full coverage of Windows 8

Previous versions of Windows have been touted as the best ever, but Windows 8 is a much bigger bet for Microsoft.  Over a billion people use Windows, but Windows 8 will require some retraining for users to get the hang of the new interface with its touch capabilities.

Review: Aggressively innovative Windows 8 forces a steep learning curve 

Microsoft CEO Steve Ballmer took the stage to pronounce: "Windows 8 shatters perceptions of what a PC is." He was referring to Microsoft's Surface tablet/PC hybrid and the touch interface that is at the center of the Windows 8 user experience. Reviewers have given Microsoft kudos for technology innovation in the Surface but cite slow performance and a lack of applications for the device.

Review: Surface, an innovative tablet stranded in an app desert

Read: Microsoft Surface vs. Apple iPad (4th gen) vs. Asus Transformer Infinity

Now playing: Watch this: Getting our hands on touch-enabled Windows 8

Microsoft hopes to continue the success of Windows 7 in business with the new version of Windows. Microsoft has sold 670 million Window 7 licenses to business and consumers since its launch three years ago, Sinofksy said.  "More than half of enterprises use Windows 7," he said.

To help kickstart Windows 8, Sinofsky said that 1,000 new PCs have already been certified to work with it. 

With analysts forecasting sales of about 400 million PCs in the next year, mostly shipped with Windows 8, Microsoft will quickly reach high volume sales. However, companies will be slow to adopt a new user interface that is so radically different from what they have been using for nearly two decades. 

Microsoft CEO Steve Ballmer Sara Tew/CNET

Windows 8 is not just aimed at preserving Microsoft's dominance in the business world -- it's also poised to begin its battle to keep Windows relevant and profitable in the new era of mobile computing dominated by Apple and Google.

Sinofsky touted the new Windows Store, claiming that it has more apps than any competing app store at its opening. That may be accurate, but for now Microsoft has less than 10,000 apps and both Google and Apple have more than 700,000 apps for their respective platforms.  "Developers are working fast and furiously to stock the shelves of the new Windows Store," Ballmer said. 

Read: Microsoft tries to play leapfrog with Windows 8

"In the case of Windows 8, seeing, touching, clicking and swiping is really believing," Ballmer said in his closing remarks. Now the billion or so Windows customers will have a chance to decide for themselves whether they believe in Windows 8.