The gameboy emulator should be portable as well, There will be a bit of work that needs to be done be there.
The core of the problem is that if you want to set data in a zune texture you need to use the type Color, the NES emulator and this emulator seem to be using uint [or short] which doesn't get the same output color wise on the zune as it does on windows.
From the tests i did it appears that if you do not use color you get no output, while if you do use Color (specifically in)
Code:
TextureName.SetData<Color>( ect..
then things work. I could be wrong there might be other ways to get things working, this is just what i have found.