afaik i only need sm 2 to do what i'm doing, which are some simple transformations and shading. i may not even need sm 2.0 to do itI would try to add as many as you can, and detect the shader model when running the game, and apply the closest one. I do that for some of my applications, to make sure it's always compatible, and higher-end computers don't get the bad end of the deal.