Just after I upgraded to Snow Leopard, a friend gave me an mbox to power some studio monitors I got on the cheap. When I went to set it up, I realized Digi isn't supporting OG mbox for OS 10.6. In my searches I found something that said if 8.0.3 wouldn't work for you, to try core audio 7.4.2 driver (I think that was the one anyway.) So now, I run my mbox through my 10.6.3 laptop using this old driver.
Upside. My stuff works.
Downside. It doesn't support my system audio. It plays both Ableton and Reason just fine, but I can't use it to play my iTunes or watch a movie through VLC. Oh well, at least I can mix!