This game is very old but there are enthusiasts out there are still play it for old times sake. I've found a forum where all the troubleshooting and fixing is done and arranged in one thread to make it easier for people who have issues to simply play the game normally.
Here is the forum wit all the instructions on how to make the game work on various Windows versions, install mods, and basically apply various customization packs: http://www.subsim.com/radioroom/showthread.php?t=212323
Note: You might need an account to be able to post on the forums to ask for help.