Alright - listen up you confused puppies:
Computers have two seperate systems - one for video and one for sound.
The only computer (or laptop) connection that carries both video and sound is HDMI. If you do not have a HDMI/DVI connector on the back of your computer, then you will have to use the VGA-composite or s-video connectors to display your PC's output on an external monitor like an LCD TV.
On both my HP and Dell laptops the display settings (Start/Control Panel/Personalize/Display Settings) allow two modes - single or dual monitor mode. Single monitor mode allows me to switch between any one of three possible video outputs - VGA-composite, S-Video or laptop screen, or a split-desktop (display spread over two seperate monitors). Dual monitor mode allows the same display on any two of three possible video outputs.
Switching is performed using the fn keys on the keyboard (fn key plus the F2, F8, etc. function key with the display marking). You guys use single monitor mode until you figure out what your are doing. Select VGA-composite or S-Video.
Non-HDMI sound to your TV monitor or sound system must be obtained from your laptop's Headphone or S/PDIF jacks. Headphone is stereo and S/PDIF is 5.1 surround sound. Headphone is electrical, but S/PDIF may be electrical or optical (laser light). You must set the sound jack that you intend to use as the default on the PC control panel (Start/Control Panel/Sound).
None of these connectors is two-way in the context of an LCD monitor - your PC cannot record a TV picture or sound from the external monitor. To accomplish this you must purchase a video converter box that converts cable TV or video+sound inputs to USB format usable by your laptop. Do this and you can turn your laptop into a Tivo recorder/DVD burner using Beyond TV, Sage TV or a variety of other software packages.