Starting at general availability, if your PC is running Windows XP, Windows Vista, or Windows 7 you will qualify to download an upgrade to Windows 8 Pro for $39.99 in 131 markets.

In addition, users will be able to add Windows Media Center for free through the "add features" option within Windows 8 Pro after your upgrade, Microsoft announced.

For all those that wil choose Windows.com to purchase an upgrade to Windows 8 Pro, Microsoft is providing a Windows 8 Upgrade Assistant, which makes upgrading simple by walking users through the upgrade process step-by-step from purchase to download and then installation.

The Windows 8 Upgrade Assistant will check to make sure a PC is ready for Windows 8 and also provide a detailed compatibility report.

Users will be able to upgrade from any consumer edition of Windows 7 to Windows 8 Pro and bring everything along which includes Windows settings, personal files, and apps. Those upgrading from Windows Vista will be able to bring along their Windows settings and personal files, and if they are upgrading from Windows XP will only be able to bring along their personal files.

Users who will choose to shop at a local store, a packaged DVD version of the upgrade to Windows 8 Pro will be available for $69.99 during this promotion.

This upgrade promotion for Windows 8 Pro both online and at retail runs through January 31st, 2013, Microsoft confirmed.

Last but not least,users who are not upgrading from a prior version of Windows and are building their own PC or installing Windows 8 in a virtual machine or a separate partition, will be able to purchase and install the Windows 8 and Windows 8 Pro System Builder product.