I hadn't seen this info anywhere else, so I thought I'd mention that you *can* use a 30" cinema display with a regular DVI (e.g. PowerBook G4 or PC)... it just runs at 1/2 resolution... 1200x800 (or something like that).
How do I know this? Because I had the display and nothing to plug it into, so I tried it. I consider myself an explorer
At this resolution things are huge... but for purposes of a presentation... or just getting by until you get the proper card, it is not bad. I'm using it in a dual monitor arrangement on my PC right now.
Half Life 2 doesn't want to come up at that resolution for some reason... but I didn't mess with it much yet.