I disagree, unless you are gonna play games on that computer in the car. All you need is PII - 350Mhz with any ATI card with TV out (at least 16MB - 8MB will be just sufficient for the job too if you are low on budget). "All in wonder" card means you will have "TV Tuner" on it. Since you will not be secrwing the tv cable on the back of it to watch TV, it doesn't make sense you pay more for the feature that you will not be using.

Which screen are you thinking of putting in front? LCD / CRT Monitor? The screen you will have in front, try to get the one which accept regular computer 15pin socket. This will not only solve your problem of which video card to get (since you will be able to use any video card then), plus when you convert any computer signal to TV (by RCA / Svideo) it changes the quality drastically and it will be quite hard to read text on the screen.

Another reason for you to go with lower CPU power is that it will be less load on the car battery.

Definately go with "Sound Blaster" from creative labs. Newer the better, the sound quality is increased as you would get newer card.

Ofcourse you can have wireless keyboard and mouse for your car, but you can also look at "ATI Remote wonder" which is basically a remote control to control a PC with one remote. Comes free with newer "ATI all in wonder" cards.

PM me if you need any help.