Windows 8 is designed to compete with Apple's iOS products such as the iPad
Microsoft CEO Steve Ballmer said that the company has sold four million upgrades to Windows 8 operating system (OS) since it was unveiled last week.
Ballmer, at the company's annual Build developer conference, said that tens of millions of businesses have also switched to the latest version of Windows.
"The level of enthusiasm and desire to learn about the new Windows 8 computers has really been remarkable," he said. "Hundreds of millions of Windows systems will be sold in the next year."
Windows 8 features a new user interface based on Microsoft's Metro design language, similar to that of the Windows Phone OS, and is designed to suit touchscreen input, along with traditional mouse and keyboard input.
Windows 8 is designed to compete with Apple's iOS products such as the iPad and will be available as Windows 8 Pro and Windows 8 Enterprise, for larger organisations.
Windows 8 has received mixed reviews from critics who say that the new operating system is too drastic from its previous versions and is confusing to use. Some experts say the radical change is risky as Microsoft could lose faithful users of its previous versions.
"Windows 8 has been designed for use on mobile phones, tablets and PC's with the purpose of providing a common look and feel, however, has Windows taken too big a gamble on an operating system which is too radically different from previous versions?" said David Akka, UK managing director for Magic Software. "Such a move could alienate the existing generation of Microsoft devotees, especially in the enterprise where Microsoft will need to drive sales through legacy devices."
The company has said that through the end of January, consumers currently using Windows XP, Vista, or Windows 7 will be able to download an upgrade to Windows 8 Pro for $39.99.
Microsoft has also released the new Windows Phone 8 OS, which is the latest version of the firm's smartphone OS, to take on Apple's iOS and Google's Android.