I bought Vista Ultimate from here a few months back for a very similar price, OEM edition. Legally because it's OEM you must buy hardware with it, I just chose a very cheap mouse.
System works just like a retail disc. One time I changed the hardware (changed the RAM) and it became "unactivated", just called MicroSoft and they gave me another key over the phone.
Extra £5 with coupon attached when purchasing with google checkout (kudos kata121212)