Today, registration is officially open for the Windows Upgrade Offer we announced in May. If you purchase or have purchased an eligible Windows 7 PC anytime between June 2, 2012 and January 31, 2013 you will be able to purchase an upgrade to Windows 8 Pro for only $ 14.99 (U.S.) which will be redeemable when Windows 8 is generally available on October 26th. If you’re still looking for a PC, check out some of our great Windows 7 PCs. Once you’ve purchased your PC you can come back and register for the offer.
Registration for the Windows Upgrade Offer is only for those who buy an eligible Windows 7 PC between June 2nd and January 31st, 2013.
Here is what you need to do to register for your $ 14.99 (U.S.) upgrade to Windows 8 Pro:
After buying your PC, go to the Windows Upgrade Offer website to register. It will ask you to select your country (details for the offer vary depending on country). You will then be asked to register with your personal details as well as information about your Windows 7 PC purchase – including date of purchase, retailer, and PC brand and model. You should also have your 25-digit Windows 7 product key that came with the PC handy as you may be required to enter this as part of the registration.
Full Information at Source