Here is my...for the most part finished 2000 Jeep Cherokee. I installed everything in Feb. and have had very few problems.
I have an athlon xp 2400 on a micro atx mb under the seat. 20gigs, 512mb, on board audio and video. XMPCR, Magellan GPS, D-Link FM Radio, XP Pro, Winamp.... In the dash is a 10.4"...under the back seat is the amp, inverters, and start-up-shutdown controller. In the back is the sub and 2nd battery.
My start-up and shutdown is controlled via a basic stamp and a switch on the side of drivers seat. The switch has three positions. 1. Down - lets the basic stamp control everything based on acc. wire. 2. Middle - completely off. 3. Up - Always on regardless of acc. wire. Normally, the switch is in 1. If I go into a store for a drink or something I flip the switch to 3 and the computer stays on running on the 2nd batter only. Pretty handy...position 2 keeps the oil change people from playing instead of changing my oil! There is a three second delay between switch postions.
Here's a link with some pictures if the attachments don't work.
http://www.4idiots.net/andy/jeeputer/jeeputer/index.htm