I've had no compatibility problems with Windows7 with the 3D applications I've tried.
Sketchup, Rhino, Vue, 3DMax, Bonzai ... there's been some more trials I've tried, but I can't remember right now. Basically - I think that if it worked on Vista it works on W7.
The only thing that you need to pay special attention to is applications that require drivers. But usually Vista drivers will work.