This was just posted by Microsoft:
… if your PC is running Windows XP, Windows Vista, or Windows 7 you will qualify to download an upgrade to Windows 8 Pro for just $39.99 in 131 markets.
How could you turn down a deal like that!?
If you prefer 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.
Such a sweet deal!