Full StoryMicrosoft has two operating system lines. There's the Windows NT-derived operating system now selling as Windows 7 and Windows Server 2008 R2. And there's the embedded Windows CE-derived operating system, currently shipping as Windows CE 6.0 R3, which sits at the heart of Windows Phone 7. The Windows CE family is already available and running on ARM processors, and has been for many years, so the assumption is that the rumor is talking about the Windows NT family: Windows (or some derivative) for ARM.
Interesting article but here is the kicker
But battery life isn't the thing standing in the way of widespread acceptance of Windows tablets. The user interface is the problem. The user interface has always been the problem. The iPad has an interface designed for fingers, the Galaxy Tab has an interface designed for fingers, the future webOS tablet will have an interface designed for fingers, and it's no real stretch to suggest that every successful tablet that will ship in coming years will have an interface designed for fingers. And it's this interface that Windows lacks.