Speaking on Tuesday at the Seoul Digital Forum in South Korea, Ballmer predicted up to 500 million users will have Windows 8 by next year, Agence France-Presse (AFP) .

Calling Windows 8 "the most important piece of work we've done," Ballmer said the burgeoning cloud computing space would be controlled by a few major platforms, including Windows, Apple's mobile and desktop environments, and "various forms of Linux" -- a thinly-veiled reference to Android.

The is currently available for download, and a more refined "" is scheduled to arrive early next month. Tablets running the touch-centric OS are expected to during the 2012 holiday shopping season.

According to AFP, Ballmer pitched software developers and hardware manufacturers on Windows 8, saying that now was the "best economic opportunity" to join the platform.

Windows 8 will almost certainly sell well in Microsoft's traditional laptop/desktop market, as nearly all new Windows PCs will come with Win 8 preinstalled.