Well, actually it is surprising (to me).
The whole idea of SLIC OEM keys was to further "tighten" an install source to a given PC/laptop, but the OEM license was "perpetual" (as long as it was installed on the same given PC/laptop and not "migrated" to different hardware).
jaclaz
It is obvious there is some difference between what Microsoft intended or designed for and what happens in the real world. It is supposed to be that if you had to reinstall Windows on your OEM computer, that when you install it with the recovery DVD, it will read the product key from the BIOS and not prompt for one and then activate automatically. I have not seen a situation where this doesn't work that way, other than reading about it on forums.