Another awkward problem

[Augury]

So after learning a little more about graphics cards, I decided to install the game onto a computer of mine which has a more appropriate setup for it... However I cannot install the game and get a message along the lines of "Cannot install without Windows Vista Service Pack 2"... Problem being that I updated said computer to Windows 7 and when I try using the Service Pack on the computer, it says that Windows 7 cannot run it because it's an update for Windows Vista... So I think the disk reads the computer as Vista (it's initial OS), but the computer is now w7. Any help in the matter would certainly be appreciated.