There is a JJ2 version comparable to 1.23 that runs natively on Mac OS. I think it's compatible with online play, though it doesn't include JCS. Demo here: http://www.dutchfurs.com/~haze/blog/.../mac/shareware

And the colors being 'messed up' could be caused by the Aero themes from Vista and 7, I remember there was a compatibility option to turn advanced themes off when a specific program is running. Just right click on the Jazz2 shortcut or exe, choose Properties, and switch to the Compatibility tab.