A DC emulator that plays commercial games on PC just got released a few days ago .1 alpha. I fired up one game and it ran great there is a pretty large playablity list of commercial games. Granted I think they recommend 1ghz I believe it is possible that with future development a DC emulator could run on a XBox fairly well.
They only worked on the project for 3 months. Kind of makes you wonder what all the other dc emulator developers have been doing for the last 5 years...
I hate it when people say that certain types of emulation are impossible and will never happen, granted I really doubt GC or PS2 will happen on xbox

But DC and I remember very clearly with N64 emulation on PC everyone said it would never happen you would NEED to have a 64 bit computer. If anyone even mentioned an N64 emulator in an emulation channel on IRC they would get flamed to hell as fake and a waste of time. I fired up UltraHLE on a celeron 500mhz with a voodoo2 and was able to play super mario, so much for the 64 bit comptuer idea
Anyway I just wanted to give a heads up about DC emulation if anyone really was interested. I know its a sucky console but there are a few good games out there for it.