An OEM license is fine if you're using the key you have on the original harware.
If you've changed the motherboard or hard drive it's less fine. (I've had this conversation with MS alot as one of their partners and they're not too sure what is acceptable for OEM licenses either).
Another problem you'll have is that if you don;t have OEM media, your license key won;t work, convenient, eh?
If you're using the original hardware (more or less) then the OEM license is valid and you'll be legal if you can find an OEM CD, otherwise you need the full version at £180 (that's my lowest price for it, anyway).
The justifiable reason is that it's not part of the license agreement.
I don;t agree with it but am explaining that this is the case.
OEM licenses are cheap for a reason. If you want to be transferring, you need a 'Fully Packaged Product' as the boys at MS say.
I wasn't discussing your philosophy.
I'm dealing in facts. An OEM edition, installed on anything other than a new PC, does not necessarily give the end result of a legal OS.
They do need to clarify what new hardware would allow it to become legit but they don;t know themselves and that comes pretty much from the top of the UK MS tree.
You don;t need to be registered.
If you're building complete systems from scratch and providing the customer with an OEM licensed edition of the OS, that's fine and perfectly legal.