While it is the case that the forum rules state that you should not discuss any bypass of EULA, I do not think anyone in this thread has implied such a thing.
To help clarify, an article on zdnet
concerning licensing says that, technically, no end user should ever install an OEM copy of Win7, and that only system builders and OEMs should install using the OPK.. It also states that any agreements are between the Consumer and the OEM, not Microsoft.
As for Retail Upgrade and Retail full packages, these can both be Uninstalled from one PC and transferred to a new PC, with the Upgrade having a pre-requisite of previous Windows license. Agreements are between the Consumer and Microsoft.
Hope this helps answer your question, OP.Edited by d0gZpAw - 10/13/11 at 8:06pm