herbold: My next guess is to use the mini-dvi to VGA adapter and connect that to the VGA port on my BeoSystem3.
I believe the mini-DVI to VGA will not work with the most modern MacBooks (sorry I don't know about the various MacMini generations) because the VGA is also essentially analogue.
There are black boxes to take the mini-DVI and covert that to VGA -- but to my tastes they are expensive. I believe you will find them discussed on threads back when Apple made this move to "simplify" production costs by dropping analogue processing.
I like the concept of distributed Apple TVs, and have been only recently (last 48 hours!) started wondering whether to use that approach for myself.
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*