LOOOL! Seems MS has slammed the door on "Win8 Free WMC Key Activation Flaw"
Sometime ago Neowin News reported on a win8 activation flaw, where people could get a legit copy of activated win8Pro+WMC over a not-so-legit KMS/MAK activated win8Pro; by using the free win8 WMC key:
However, it seems MS had finally made up their minds to patch the loop-hope - today people in MDL(and as they mentioned, also on other forums) reported that, when they try to add WMC to KMS/MAK, or even Dreamspark-activated win8Pro and activate the win8Pro+WMC, it returned with a fail-error:
Unable to activate Windows 8 Pro with Media Center. (Error code: 0xC004C4AA)
What it means and how to fix it
You might see this error after you used the Add Features to Windows 8 app to upgrade your current edition of Windows. The Windows 8 Pro with Media Center edition can only be activated on PCs that had Windows preinstalled, or Windows was purchased on the Windows website or at a retail store. To fix the problem, you need to install Windows with the product key provided to you in an email or with the DVD. If you think you have received this message in error, contact a Microsoft Customer Support representative.
Seems if people wants to add WMC; he could only do so with a pre-installed edition, or a win8Pro activated by a retail key.