If you want to connect your pc to tv via the s-video port of your video card, then install the nvidia driver and edit xorg.conf with the options shown on the screen section. In my case I had to build a cable to convert s-video to compsite.
http://www.epanorama.net/circuits/svideo2cvideo.html
### Comment all HorizSync and VertSync values to use DDC:
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Acer AL1912"
DisplaySize 370 300
HorizSync 24.0 - 80.0
VertRefresh 49.0 - 75.0
Option "dpms"
EndSection
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "Videocard vendor"
BoardName "nVidia Corporation NV34 [GeForce FX 5500]"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 16
Option "TwinView"
Option "SecondMonitorHorizSync" "30-50"
Option "SecondMonitorVertRefresh" "60"
Option "MetaModes" "1024x768, 1024x768; 800x600, 800x600; 640x480, 640x480;"
Option "TVStandard" "NTSC-M"
Option "TVOutFormat" "SVIDEO"
SubSection "Display"
Viewport 0 0
Depth 16
Modes "1024x768" "800x600" "640x480"
EndSubSection
EndSection