Personally I wouldn't download an ISO.
A couple of reasons,
1) Just because it's an ISO you don't know that it hasn't been modified in any way, there could be loads of viruses hidden in the ISO file.
2) If your using a torrent, then if you upload then your really in trouble as you'll be sharing to people who may not have a key.
3) Your ISP may be monitoring your traffic as Virgin Media do and they may be able to inform others that you have been downloading content. Also under the law the ISP is obliged to share (abeit after a court order) any details of your traffic. While you may be able to longer term prove your innocence it will cause you grief.
4) One case recently when people downloaded adult content, hidden inside the package was a game (pinball if I remember correctly). The company who own the intellectual property for this game have employed lawyers to persue people for money in relation to this rather than go to court.
Best way is to try to find a friend who has the game and borrow it to install, otherwise, I'd wait until it is on the bay or the MM here and buy a copy second hand.
Probably not the response you wanted, but now you have the information you can make your own choice.
Cheers
Taff