Hi, I originally bought Office 2010 Pro+ from Software4students about a year ago and they are genuine MS discs with key, and it did say for one PC only, so I did realise it was OEM - but at the price it was still a bargain.
A few weeks ago I decided to upgrade my PC and was waiting for W8 to be released but having read what MS are planning for licencing with 8 (as far as apps and second party software are concerned) it seems that 8 is becoming a clone of Apple software - please correct me if I'm wrong. Instead I decided to go with 7, and as I've been running Vista Ult (32 bit), 7 Ultimate (64 bit). I checked on S4S's site and saw the prices I've quoted above so bought from them. Again it was genuine MS discs with key and I'm now running it on my set-up PC with most of my other software already installed.
I have no problems with S4S, they are MS partners I believe and they also do other software, Adobe included (if I could afford it I'd get CS5 from them).
As an aside, when installing software on the new set-up I tried the Office 2010 disc and it seems to have installed and authenticated ok, I will let you know if it's OK when I actually come to use it.