Microsoft today announced it will offer three different editions of Windows 8: Windows 8, Windows 8 Pro and Windows RT. Two of those versions will be available as upgrades, Windows 8 and Windows 8 Pro. Those two versions will run on 32 and 64 bit PCs and tablets processors. Windows 8 will be the right choice for most users, but Windows 8 Pro adds some new features such as “encryption, virtualization, PC management and domain connectivity.”

Windows RT, the newest edition of the Windows family, will be the Windows 8 version optimized for tablets. Windows on ARM (Windows RT) will come pre-installed on desktops and tablets powered by ARM processors. This version will include “touch-optimized desktop versions of the new Microsoft Word, Excel, PowerPoint, and OneNote”, and will not allow installation of x86/64 and desktop software.