fatson, two things...
1.) Those demos were done on a Geforce2, which is supposed to be two generations behind the NV2A.(the graphics card thats going to be used for the Xbox)
2.) Those demos were demonstrating the Xbox\'s lighting capabilities, and how it is capable of show several objects on screen at a time.(There were like thousands of butterflies in that demo)
Anyways, just wait for Gamestock..