A good way to use multiple computers for presenting your shows to your audience with out spending a fortune on professional video switchers is by using a KVM switcher. This one that I have shown here is similar to what we use at the Orchard. What we do is to take the video out VGA cable from the computers and attached them to the VGA or DVI inputs behind the switch
and Hook the switch's video out to the Projectors used in showing the presentation to the crowd.
This method makes it easy to have multiple shows running at the same time but on different computers to prevent resource sharing conflicts. So what we have going is that we have a DVD player with a RGB (red green blue) video out signal going into a converter that convers the signal into a VGA (which is what our KVM uses but I would think that the newer DVI ones would be better), and that signal goes into port two, the main computer goes into port 1 and if you have a guest who runs his own presentation, that can goe in one of the other two open ports. Then when needed just use the push button switcher to sent the video signal from the appropriate device to the projectors. Our Videographer starts his videos with a black screen, this way I can switch between the computer and the DVD player without the audience noticing the transition. This keeps their focus on the service instead of the presentation ofthe service and keeps the momentum going. I hope that some of you find this usefull as it is the presentation as well as the speaker that keeps the audience engaged in the service.