You can't give them the license sticker because the license number is in the CMOS/firmware. You install Windows with the "HP key" or "Dell key" and it automatically finds the license number on the machine. That's why OEM licenses are given at a discount. They are not transferable.
Incorrect in my experience (from a technical standpoint): an OEM Windows install key will just work with an actual windows install CD/DVD (although for XP you need a genuine OEM CD--which Newegg sold). Now, legally, you are correct -- OEM licenses are not transferable from box to box.
Have you ever read up on Amdahl's law?
I'll see your Amdahl's Law, and raise you Gustafson's Law.
"Protozoa are small, and bacteria are small, but viruses are smaller than the both put together."