Microsoft has announced its Windows Upgrade Offer allowing consumers to upgrade to Windows 8 Pro for $14.

The new of the bargain upgrade price comes hand-in-hand with the launch of the Windows 8 Release Preview. The Windows Upgrade Offer will start tomorrow, 2 June, in 131 markets including the US and Canada. See alsoInstall Windows 8 Release Preview.

Windows 8 Release Preview

Microsoft said: "Are you really excited about all the new PCs available today but thinking about waiting for Windows 8? Well you don’t have to."

The move brings Microsoft more in-line with how rival Apple handles upgrades with its Mac OS X operating system. For example Mac OS X Lion is available for $29. See also: Windows 8: the complete guide.

Consumers who buy a PC with Windows 7 Home Basic, Home Premium, Professional, or Ultimate pre-installed and have a matching and valid OEM certificate of authenticity will be eligible for the $14.99 upgrade price.

This will take users up to Windows 8 Pro, the more advanced OS of the two desktop OS versions and includes 90 days of support from Microsoft. The Windows Upgrade Offer will end on 31 January 2013.

Windows 8 Advisor

The upgrade will be fulfilled when Windows 8 is fully launched. Although there is no set date for this, the firm said that Windows 8 will enter the final phases of the RTM (release to manufacturing) process in about 2 months.

"If we are successful in that, then we are tracking to our shared goal of having PCs with Windows 8 and Windows RT available for the holidays." it said.