Windows 8 will be offered to PC users in standard and Pro editions, backed up by a pre-installed ‘RT’ version for tablet computers based on the ARM chip, Microsoft has announced.

The plan is a helpful streamlining of the confusing array of versions of Windows 7 that appeared at launch in 2009, including Starter, Home Basic, Home Premium, Enterprise, Professional, and Ultimate.

The standard edition – called simply Windows 8 – will be the version pushed at most consumers, including those upgrading from Windows 7 32-bit and 64-bit. This will offer a range of Windows 8-specific features including Internet explorer 10.

Pro will add to this a number of more technical features BitLocker file encryption, an encrypting file system, support for Hyper V, group policy and remote desktop. Pro users that want the Windows Media Center will be able to add this as an upgrade.

The third and brand new flavour will be Windows RT (also referred to as ‘Windows on ARM’ or ‘WOA’), designed as a pre-installed version for tablet computers running the ARM chip. It will also run ARM-based laptops though these have yet to appear.

Despite the common Windows moniker, RT is really a parallel version of Windows that sets the operating system’s future course as software oriented towards devices other than the traditional PC.

The name references WinRT (Windows Runtime), the programming environment for the OS’s dedicated Metro apps, a nomenclature that might confuse some users to start with. Microsoft’s view is that this version will only be available with a new device and so consumers will only encounter it as part of that buying decision.

“We have talked about Windows 8 as Windows reimagined, from the chipset to the user experience. This also applies to the editions available – we have worked to make it easier for customers to know what edition will work best for them when they purchase a new Windows 8 PC or upgrade their existing PC,” explained Microsoft’s Windows communication manager, Brandon LeBlanc.

Finally, there will be a ‘bulk’ edition of Windows 8, basically a packed version of Windows 8 Pro for enterprises.

Upgrade pricing is some way from being announced but is expected to be along similar lines to Windows 7.