What's there to emulate, really?
As far as I can see, after reading the specs, I don't really see the difference between the X-Box and a PC.
Ofcourse I have no idea on wich audiochipset it will have.
Or exactly HOW modified the GeForce3 Chip will be....
But in my eyes it looks just like PC....
So I really don't think (I'm probably wrong here, but what the heck...) there's any need for an emulator, unless you want tog run games on Mac or in Linux or something.....
