On the 2nd September I put together an Win 8.1 Pro WMC iso using the instructions posted on this site. Win 8.1 WMC Create activate the Windows 8.1 Professional with Media Center using you free Media Center key iso used -> MICROSOFT.WINDOWS.8.1.RTM.X64.ENGLISH.DVD-WZT. extract install.wim your iso. perform the following procedure in CMD. dism /mount-image /imagefile:e:\install.wim /index:1 /mountdir:e:\mount Dism /Image:e:\mount /enable-feature /featurename:NetFx3 /All /Source:k:\sources\sxs /LimitAccess dism /image:e:\mount /set-editionrofessionalWMC copy e:\tokens.dat e:\mount\Windows\System32\spp\store\2.0 /y copy e:\data.dat e:\mount\Windows\System32\spp\store\2.0 /y dism /image:E:\mount /set-productkey: (using you free Media Center key) dism /unmount-image /mountdir:e:\mount /commit add file ei.cfg to sources in your iso. This allowed me to reinstall Win 8.1 Pro WMC on the machine that product key was licenced to. Yesterday I inserted KMSpico's latest "OEM" folder into the "Sources" folder of my iso. I installed it on 3 different physical Machines (not VM). All are activated, installed Office 2013 Pro, restarted machine, Office now activated. When I checked the product key it was not my original WMC key. Effectively I now have a KMS activated Win 8.1 Pro WMC iso that will instal on any PC. Thankyou to Heldigard for KMSpico and Murphy for iso creation. Hope this helps those who have been looking for a way to activate Win 8.1 Pro WMC using KMS.