Video wiring
The component cabinet and the plasma sound nice, however, the builder dropped the ball on the wiring.
You need 1 coax for composite video,
2 coax for s-video, and
3 RG6 coax for component video.
If the builder was smart and installed conduit, you can pull the new coax to hookup the plasma. If not, you will probably have to run it up through the ceiling and down to the TV location.
It would also be nice to have an HDMI connection to the Plasma, but it is difficult to get this to work over 40-50 foot distances.