i dont even understand what the big deal about xna is, except for maybe the ability to make open development for the xbox a little closer to realisation. Its not like there isnt the same type of system in several other places... ogre, crystal space, all of them do the same thing and more for free, there actual full fledged engines, not just framework api's that aid making a 3d engine, if there is anything, it will just make it easier to make a 3d engine.