The Windows RT version of Surface will go on sale first in 32GB or 64GB versions. It will be priced at the same level as competitive Windows RT tablets from other makers, Microsoft said.

The Windows 8 Pro version will ship three months later in 64GB or 128GB versions, and is expected to sell at the price of ultra portable PCs, Microsoft said.

A for both Surface tablest is posted on Microsoft's site.

Microsoft CEO Steve Ballmer called the tablets actual PCs because they are based on Windows 8. "The Surface is a PC...a tablet..and a new experience," Ballmer said.

Windows RT will run ARM chips, while Windows 8 Pro will function on X86 architecture. The ARM architecture is widely used in smartphones and even Apple's iPad, while Intel has been the biggest maker of X86 chips for laptops.