I think you are right in your interpretation. But, on my side, I am lucky Computer A: Vista Computer B: Windows 7 In my drawer : Windows XP Pro Retail, never installed/activated. So, in my case, I decided to "apply" my upgrade license to Windows XP, giving me a full Windows 8 Pro taht didn't replace any in-use operating system. So I can install in on any computer I want, just 1 copy at the time, and still keeps my right to roll-back the computer to previous OS since the upgrade license was not applied to the one on the computer, but rather on the I was keeping and which was not installed.
So it is impossible to cheat Microsoft?, A key WMC used in a PC can not be used on another PC?, This means that somehow keep information related to the physical components of the PC when you turn the key WMC.