Most of my older ones run fine, just not RCT 3 (and to an extent Star Wars KotOR 2, but that's got some bugs too, and was incomplete really if you know the plans they had for it...) Weirdly, my first ever game for the computer (a more modern version of Pong from the 90s I think where they made it 3d with cool features like Molehills and Polar Bears on some levels) runs near perfect, just the music stops as soon as you start a match, but other than that it runs perfectly.