Theres huge difference between buying a COA sticker and a "Must be distributed with a new PC" OEM Version, i don't know what MS say about the latter, but if you get a disk, and this is the important part, a real license thats the difference, as mentioned before a COA sticker is not a license.
Lets say purely for the sake of late nite/early morning discussion, and nothing else, you ended up in court with a small business that had their OS's installed from OEM verions bought with .99c audio cables. MS's lawyers holds up the box which says 'must be distributed with new pc" he asks if you bought it with a new pc, i'd feel uncomfortable giving an answer of no i bought it with an audio cable. Its there in large letters on the front of the box,
Still i wonder about the legality of the OEM version, since it quite clearly states new PC on the box, presumably there must be something to it that allows this model, $139 is a lot more believable than $55
FYI :
I'm sensing enough legalese in the websight you posted to cofuse anyone. I didn't see anything about needing to be a Certified Microsoft System OEM on that page, which I assume is just paying them a big fee.
"Legal PC manufacturers "
If you want to become one,
http://www.microsoft.com/oem/sbp/memben.mspx
You also have to be a bonafide customer of one of their distributors. Its free to join, you just have to buy their software in some quantity.
Also if you buy the OEM version you have to do a clean install, upgrade isn't possible , but doing a clean install is usually better so its not usually an issue, just something to be aware of.
heres the differences listed for home and pro, btw
http://www.winsupersite.com/showcase...p_home_pro.asp
As for the charity PCs being activated with no problems, you could go on google and find half a dozen serial numbers that would activate fine too, and install SP1 use software update etc, the process actually allowing the software to activate, is not a measure of its validity.
to recap on just the interesting bits
COA sticker = not legal and not worth the paper its printed on if it wasnt stuck on the PC by a PC OEM certified by microsoft, end of story, its quite clearly stated on MS's site in plain english.
Shrink wrapped OEM version bought with audio cable with giant "Must be distributed only with a new PC" on the front = well you get a license, presumably theres some loophole allowing for this, and the price is close enough to the retail version considering irs partially crippled due to the clean install, and possibly you won't be able to use it to upgrade to the next OS, its been such a long time since i had to to that, i can't recall if an OEM version is able to be upgraded from.