It is actually a setting of the video driver in your OS.

For most video drivers,  you go to the "Settings" tab of the "Display Properties".  From there,  you click on teh "Advanced" button,  and go to the "Displays" tab to select which displays to use (At least for the ATI video drivers).  For the NVidia drivers,  it is similar,  if not the same.

I looked there, but there was not an option for "NTSC" or "S-Video" output - just the ability to switch between the laptop display and an external (xVGA) display via the VGA port on the back of the laptop.   I am running the latest video driver from Dell, so I am confused as to how to enable the TV-out.   Does a TV actually need to be plugged into the source while I reboot, I wonder....?

" Does a TV actually need to be plugged into the source while I reboot, I wonder....? "

Yes, of course.