Sorry if this has been answered before, but everything I searched for was related to the free loophole from before. Basically I just installed Windows 8 and activated with KMS. If I go to "add features" and buy Media Center for $10 will that work? I am not sure if they blocked the previous media center keys that were given away during the free period or if they bocked all media center upgrades from KMS activated machines. Thanks!
WMC installed on KMS activated system cannot be activated online, you might have luck activating the WMC key by phone after upgrading.