It should probably run without the service pack update, its just good to have em for increased compatability and all that. Otherwise, find someone with a different copy of Windows to yours and install that on your system, with their CD key. Not that I condone piracy but if you are having trouble with your OS, you have to know someone with a 'real' version of it.
I'm actually using a real version of Win2000 with an internet CD key, since mine is lost in the wilderness somewhere, which annoys me, but it comes with SP3 so I can't complain. I wouldn't worry about the service packs until you get the game and it doesn't work.