Area51ireopen is probably correct, As long as you do not have 64BTI Vista) And you have the game installed, right click the icon you use to start the game -- go to compatibility tab - and turn on compatibility mode, it the drop down menu you should find 95. You many also need to experiment with settings on this tab. I am running an ancient version of space invaders on my Vista machine (32BIT) successfully in this fashion.
Can you name the game for us> the suspense is killing me