2 Monitors are supported in OSX. Actually at work I have 3 monitors on the same box. But the problem is the apple video connector you (father) have on you apple displays. The connector that is on the apple displays is not a standard VGA. It sends the video signal, power, and USB down the same cable, which is why you cannot attach one of apples wonderful monitors to a VGA video card. You can only attach these monitors to the standard apple video card, which runs off of the AGP bus on your mother board. Your board only has 1 AGP bus and therefore can only support one AGP card, and therefore can only support 1 apple video connector card. This means that you can only have 1 apple monitor hooked up to the computer at once. This is not a limitation of the software (OSX). It is the limitations of hardware.
This being said, there is no problem (except for the looks) of having one apple monitor and one (or more) regular monitors hooked up, you just need more video cards. (non AGP). This is what we had to do at my office.
As of my knowlege there is no connector to connect an apple monitor to a VGA card. I may be wrong, but I have looked very hard at no avail.
I hope this answers your question.