Windows 8 is still in beta (consumer preview). You can download Windows 8 Consumer Preview here. When Windows 8 is released, there will be three editions.
- For PCs and tablets powered by x86 processors (both 32 and 64 bit), we will have two editions: Windows 8 and Windows 8 Pro.
- Windows RT is the newest member of the Windows family – also known as Windows on ARM or WOA. This single edition will only be available pre-installed on PCs and tablets powered by ARM processors and will help enable new thin and lightweight form factors with impressive battery life.
To find more detail, including upgrade path from Windows 7 to Windows 8, check out the post here.