FWIW:
MS's site says that if you bought windows 7 machine after 2 June 2012 then you can get the
windows 8 pro upgrade for $14.99 by registering on their site.
Buy a Windows 7 PC between June 2, 2012 and January 31, 2013. *
Windows 8 upgrade offer - Windows 8 special offer
*Offer valid...