I have a lacie electron19blue III and an apple 17 inch studio display (crt-clear). I am puting the studio display to the adc slot, and the lacie in the vga slot. Both monitors turn on and work, but they show the exact same thing, and I cannot have different resolutions for each. I am assuming that I just don't have dual monitor support. When I have both monitors plugged in, the montors prefs don't give me that many options...
I lookd at the stats on my computer and I noticed that the next upgrade for the video card at the time (which would have come standard on the dual 800's) is the geforce 2mx Twinview. mine is not the "twinview". I would assume that that would mean that I my regular geforce 2mx card doesn't support it.