sorry, I wanted to quote and answer, but the message got too long then (limited to 10000 characters. So, hopefully you find what you need ;-))
If you want to watch TV while driving, there's some different solutions now which offer you this.
The best one in my eyes is this: http://car-solution.bei.t-online.de/TV_Modul.html
because this is a little black box which can be installed in minutes, can be reversed without any problems, and is fairly cheap.
$ 400 for such a simple thing... well, the guys at NavTV all drive big cars, I bet ;-))
The Video module is the same part for all over the world; it's capable of receiving PAL and NTSC signals, and this is switched regarding the country the car is sold to.
If you are (as me) in Europe, the module is connected to the PAL input, and the NTSC input is left blank. If you are in the US, it's vice versa.
Now, the used input is controlled by the speed signal which means that the screen is blanked when you are driving.
Surprisingly, the other composite input can be used without any problems while driving. There's a pin in the white plug that needs to be connected to ground, and then the module switches permantly to this input. Permanently means that the screen shows the signal of the second input as long as the "switch" is connected to ground, it doesn't show anything from the system.
This is the easy way to hook a computer via TV out to the screen, but the quality of the picture is of course not very good; it's okay for movies and this stuff, but the windows desktop e. g. is unreadable until you use VERY big letters.
Now, the information of NavTV seems a little bit irritating to me:
The video module sends a standard RGB signal to the headunit, except that it doesn't use separate sync signals like a standard VGA card(screen combination (H-sync and V-sync), it uses sync-on-green instead.
The resolution of the Sharp TFT is 400x240(234), 60Hz; so if you build a mini circuit (less than two dollars!) which combines the V-sync and the H-sync signal to the green signal and you also have a VGA card capable of the needed res and frequency , you're there. No need of special (and expensive) signal switchers.
This allows you to connect a computer directly to the RGB signals which give you a much better picture quality than connecting the TV out to the composite inputs.
Further questions? No problem ;-))