Halo 2 Xbox 360 vs. Xbox Comparison
Take a look at this side by side comparison of how Halo 2 looks running on the Xbox 360 compared to the original Xbox.
360 is a little less gritty but not by much, i still like playing my original xbox from time to time, it's good to remember your roots...
The XBOX graphics aren't as crisp and clear, you can tell when they show Master Cheif's armor at one point. Also, the windows of the spaceship 'flicker' on the XBOX, and on the 360 you can see out into space just fine. Not a huge difference, but a nice one.