That copy looks right. It jsut includes the latest SP and all which is convenient. If they have a non-service packed edition and it's cheaper I'd get that...you can install the SP for free from Microsoft Update it just takes a bit of time.
Ubuntu is available here -
http://www.ubuntu.com/download OR
https://shipit.ubuntu.com/
The difference is if you download you gotta burn it to a CD and then install it. Or you can have them ship free CD's to your house (but it takes a good month at LEAST, mine took almost 2 months I think).
Oh, well that's semi-not OK. They may let it slide...but technically since it's a different operating system and it wasn't originally on the computer I dunno. If it had been XP Home agai I may be singing a different tune.