Xbox Emulator for OS X?

Does anyone know of a good one (or any at all, for that matter)? When I get a faster Mac, it would be really cool to be able to play Halo and Halo 2. And while I doubt it, is there any Mac software that can read Xbox discs?

I have yet to see a XBOX emulator for Mac, mainly because I've never looked. If you find one, I would highly suggest using a ROM due to seek speed or a program that is configured to cache a lot more than the XBOX's whopping 64mb. It's legal if you own the game, so don't panic.

Good luck!