If you've been wanting to upgrade to Windows 8 but baulk at paying then, firstly, you're a bad person but, secondly, now your opportunity's here. Microsoft just screwed up and handed out a free activation key for the OS.
Microsoft is letting Windows 8 Pro users upgrade to Media Center for free until January 31st. Neat. But in so doing, it's handed out a code that will fully activate any copy of Windows 8. Oops. The Verge has even tested it out and is confirming that it works.
If you want details of how to do it, head on over to Reddit. [Reddit via Windows Wave via Verge]