The most obvious reason to install video in the car is so your passengers can watch movies, and with a computer, the in-car DVD experience can be even better.
DVD entertainment is the major driver of in-car screen sales. In-car video entertainment was once rare, but now you can purchase a DVD player and two headrest screens for the rear passengers for under $300.
But this cheap solution doesn't give you the best DVD experience possible. In-car portable DVD players are limited. Most of them include only stereo sound, not surround sound (Pyle, at http://www.pyleaudio.com, and Phoenix Gold, at http://www.phoenixgold.com, are notable exceptions), and most of them are limited to composite video output, which is the lowest acceptable video quality.
A modern personal computer is a much more powerful DVD player. For about $50 you can get a full-featured software DVD player that does progressive scan conversion (a method of enhancing the visual quality of DVD video for flat screens and computer monitors), offers surround sound, and can be set to play DVDs from any region (U.S., Europe, etc.). Computer-based DVD players can drive high-resolution screens at the full DVD resolution of 720 x 480, and even higher on larger flat screens.
There are several approaches to getting DVD drives into a car. Many in-car computer enclosures have an integrated CD/DVD drive, either tray-or slot-loading. However, most computers are too large ...