This is a silly question, but why won't my new 20" apple cinema display work with my old sawtooth? I know it comes down to the graphics card, an ATI-Rage 16MB ... thing. Obviously, it's not compatible. My question is, why not? I mean, what is it about my old video card such that, when I hook up my new monitor to my sawtooth, when I turn on the computer, the monitor simply won't work? How does the display itself determine whether its requirements are met?