Ok. Sorry about the delay, but here?s what I did.
If you look in the first picture you can see the center console of my car. The three black buttons on the front let me control winamp with my fingertips while driving. They?re set to play/next track, pause/stop, and next playlist. The interface program is comtrol, which can be found here:
http://diba.hotbox.ru/comctrl/ It lets you have up to 15 buttons run off the serial port. I use 3 for winamp and the rest for other system functions.
<img src="http://s95238930.onlinehome.us/cconsole.jpg" alt=Closed Center Console'>
Next you see the console when opened. I know it?s a mess but it gets the job done just fine, and you can?t tell anything is in there when it?s closed. The blue arrow is pointing to the power supply. That should give you an idea of how small it is. The 60mm fan right above it is the CPU, and is the only fan on the system. The switch on the top right is for powering the unit off of an AC adapter when I?m loading software or working on the system and don?t want the car idling for 2 hours .
<img src="http://s95238930.onlinehome.us/console.jpg" alt=Open Center Console'>
The next picture is my dash and head unit. The only noticeable modifications are the two power buttons on the bottom and the set of programmable buttons on the top for the navigation system. The rocker switch on the bottom left controls Acc. power to the voltage dropout regulator (more on that later), while the red button on the right is a manual power button for restarts and such.
<img src="http://s95238930.onlinehome.us/dash.jpg" alt=Dash'>
The last picture is of the screen. 7? LCD with touchscreen. All the cables are routed down through the inside of the left A pillar, leaving no visible wiring. This is a screenshot of the GPS nav. system and mapping software.
<img src="http://s95238930.onlinehome.us/screen.jpg" alt=Screen'>
The best part about this system is that you can?t tell it?s not factory from outside of the car. All the buttons are inconspicuous and you can?t see the screen unless you get on your knees and look up at the roof.
For the Dropout regulator you can read about it here:
http://www.mp3car.com/products/itps.html
Needless to say, you have to get one no matter what :-)
Since you?re only thinking about playing mp3?s you could just go with a 2-line lcd display, and a USB interface. The good ones start around $50 and come with sample code, although I?m sure you can find some winamp plug-ins out there already. A quick search turned up this website, but there are plenty more out there.
http://www.performance-pcs.com/catal...a3e9e4791e4f27
For the audio I spliced into the connection between my in-dash 4-disc changer and the line-out port on my sound card. A 3-pole double-throw switch lets me go back and forth between the two.
If you have any questions just ask, although a lot of it you won?t run into until you actually start building it.