"We've reimagined Windows and we've reimagined the whole PC industry," Ballmer told Reuters Television early on Thursday in New York ahead of a launch event for Windows 8 and the company's new Surface tablet, which both go on sale to the public on Friday.
"In addition to notebooks and desktops, we introduce the PC as tablet," said Ballmer. "Work. Play. Tablet. PC. Boom! One product."
The world's largest software company is desperate for the new-look, touch-friendly Windows 8 to grip customers' imaginations, as it looks to regain ground lost to Apple Inc and Google Inc in mobile computing and shake up the moribund PC market.
Microsoft is doubling down on its bet with its own tablet called the Surface, available only through its own stores and website, which will challenge Apple's iPad head on.
"We have a device that's uniquely good at being a tablet and a PC (with) no compromise on either one," said Ballmer.
Ballmer, who took over as Microsoft CEO from co-founder Bill Gates in 2000, is moving the company away from its foundations in software to become more of a hardware and services company, like long-time rival Apple.
"We're all in on this," Ballmer said, adding that 10,000 applications would be available at launch and that Windows 8 devices would be available at a variety of prices.
"You'll find these things everywhere this holiday season. You walk into any retailer that sells electronics, other than an Apple retailer, you will see Windows 8 machines all over the place from Acer, from Samsung, from Dell, from Toshiba, Sony, Lenovo and many others."
Ballmer added he expects more Windows devices to be sold this quarter than Apple or Google products. That is not surprising, given that 90 percent of the PCs sold across the world run on Windows.
Microsoft shares were up 0.5 percent at $28.04 on the Nasdaq on Thursday morning.
(Reporting by Nick Zieminski and Bill Rigby; editing by Matthew Lewis)