sorry there is no PS2 emulator for the xbox and probably won't ever be one. i read that the xbox would have to be more powerful to be able to emulate the ps2.
When you run Emu stuff, you genrally have to step back a whole system to b able to run it ok. I.e. When the PS2 was released the PSone would be about emulator ready. The reason behind this is that if you are running a PS2, it takes 100% of that PS2's resources, if you are trying to run that on an xbox you still need to run the stuff that drives the xbox as well at the PS2 stuff so not giving you enough to run the games properly (well, that is as basic as I can describe it). Also there is a whole lot of conversion having to happen on th fly, this is why the same above is true when running Emu on PC, your PC could be the fastest and th best but i bet you that you wont be running any PS2 games as good as they are on the PS2 yet, but give it a couple of years and no sweat. Humm, I'll get back in my box now