Just for fun, I've tried to squize Mupen into C# and got it working; albeit slowly. For graphics I've ported (attempted) LemD3D plugin to XNA. As I absolutely do not know what I'm doing results are not what could be expected. Problem probably that I've tried to use precompiled pixel shaders; and not doing correctly. If there is any interest to try to take this further by someone who knows XNA I might up up the sources somewhere. Anybody ?
Oh, here are some pretty pictures