Thinking about it now, I definitely do think a twin mac system frame locked together with t th2g would be fine. It free's up an output on each that doesn't need to be high res so all the processing is only for 3 outputs per computer. Again on the graphics card though, what really is the best out there? I had thought about a wide angle but the distances are up to 60ft from centre to edge, and the client doesnt want anything in the centre of the room, however one facing directly up hung in med air might be ok for top image, provided it looks fine and doesnt block projectors down low. I've been looking at this website from a man called Paul Bourke and he has some very interesting study done on projection using domed mirrors. I'd need very bright projectors and some seriously shiny mirrors though. I think it might work?