wiring a ceiling suspended projector
Before doing a lot of wiring, I ask what are the cable, DVD, and computer outputs? Do all have HDMI? How are you switching from one source to another?
For most of us, I believe HDMI is the current standard, with switching through an audio reciever or matrix or similar device. If you have HDMI from your sources, I see no reason to install S-video, composite, or even component. Perhaps there is some value in running some extra wires in case you ever need some analog signal such as VGA, component, RGBHV, whatever. You may also want to run cat-5, just in case. Wire is cheap. Until you actually need it, however, there is no need to install any particular connectors. Stick with HDMI as your current interface of choice.
If you don't have HDMI from all your sources, you should consider an up-converting reciever. They are becoming pretty economical at this point.