Windows 7 went public in October 2009 - came at the software giant's annual Worldwide Partner Conference in Toronto.
Communications manager Brandon LeBlanc said the company "confirmed that Windows 8 is on track to release to manufacturing (RTM) the first week of August" and "will reach general availability by the end of October."
Windows 8 will be available in 109 languages across 231 markets worldwide, he noted.
The latest version of the operating system that is the norm for personal computers will also be used on many smartphones and tablet computers, including Microsoft's own Surface tablet to be launched this year.
It "is simply the biggest deal for this company in at least 17 years," Microsoft chief executive Steve Ballmer told the Toronto gathering, referring to the launch of the game-changing Windows 95 operating system.
It's the glue, it's the foundation of everything Microsoft is built on."
Windows 8 allows users readily to store and share personal data among various devices under the "SkyDrive" cloud computing service. Rivals Apple and Google offer such services.
The new Microsoft system will support a wider range of devices, including touch- and stylus-based smartphones and tablet PCs as well as desktop and laptop machines.
software giant has been trying to expand its presence in the booming software market for smartphones and tablets, which is currently dominated by Apple and Google.
Cloud computing refers to the popular trend of using software as a service hosted online at data centers instead of downloading and maintaining programs in personal machines.
Web-based email services such as Gmail are common examples of cloud computing.
Microsoft said separately it would release a new version of its popular Office software suite called Office 365 Open, which allows its partners to resell and get additional revenue from the product.
Microsoft also said it would acquire Perceptive Pixel, which makes large-scale, multi-touch displays.
The company makes what it calls "the world's largest projected capacitive, optically bonded multi-touch display," which is 82 inches (two meters) in size.
Terms of the deal were not disclosed.