Here's what we know so far about Windows 8 pricing. If you want to upgrade from XP, Vista, or Windows 7 to Windows Pro, it will cost $40 up through January 31, 2013, after which time the price will go up. We also know that if you buy (or already purchased) a qualifying Windows 7 PC between June 2, 2012 and January 31, 2013, a Windows 8 Pro upgrade will run $15. Other than those two promotions, Microsoft hasn't released any official pricing info. What gives?