Get yourself a Receiver. They have numerous ins and outs of all different kinds (composite, HDMI, Optical, Coax etc). Then everything is put out to the same set of speakers and 1 screen. Switch between sources using a remote, then control each source with its own remote, or buy a fancy all in one.
Might need a few HDMI -> DVI adapters but it would work, it's probably the expensive option though.