www.bungie.net | halo.bungie.net | bungiestore.com
Is there one? If so, where? If there isn't will there be one? If there is going to be one one but it isn't out yet when will it come out?
There is no Halo CE for Mac. To be honest, I don't think there ever will be either...I have no idea why. Perhaps ask some questions over at the Gearbox forums.