Not 100% sure ignatz, I personnaly thought they would work, I do know of a way to get them working legally but that is not for discussion on a public forum
Just to clarify, there's no difference in discs for OEM and retail anymore, in terms of licensing. Gone are the days of XP when you needed a retail or OEM disc. Not since Vista's release have we had to worry about that wrinkle in the clean install process.
I can't confirm if some OEM's BIOS lock their discs, because I use OEM discs for one and only one reason...drink coasters.
There shouldn't be any "not liking my key" as people are stating, as long as you aren't trying to use a Professional key on Home Premium, etc. The keys will be accepted. Possibly, if they have been used recently, you may not be able to activate online...but a simple phone call fixes that.
Going by typical accepted practices, don't put in your key during the install. Enter it later, once you get the system up and running, and there should be no issues. I've used the Digital River .isos and TechNet isos, to install on everything from OEM systems to custom builds without any issues.
The simplest way for those of us who do many installs of various types, is to create the USB flash drive installer with all versions and both platforms. That method also works with any type of legit key.
