Around 1999, I installed a half/mini-AT computer mainboard (a little less than 12" square if i remember right) under the driver seat of my 95 Camry as a dedicated MP3s player. In that setup, I actually had a 17gb 3.5" IDE drive hanging from springs in my center console, with a long IDE ribbon cable going out under the edge of the console to the mobo below. It ran a stripped down version of win95 so boot time was about 10 seconds (including POST!) and defaulted to a playlist of all MP3s on shuffle. LCD text display (40x4 chars - almost exactly single-din size, so it fit perfect below my single din head unit) running from the parallel port, and a numeric keypad on an old carphone stand for controls - ff/rew, changing tracks, play/pause, and toggling shuffle. If I remember right, it was something like an athlon 200mhz, maybe 16 or 32 megs ram and just used onboard sound to minimize height of the board. Onboard sound was fine - I'm no audiophile and my car had too much road noise to tell the difference anyway. Tiny little 120w psu (AT so it had an actual power switch, not the soft-power ATX stuff), and a simple 100W 12v inverter to power that via a few relays and its own power circuit (probably 12-14awg). Since it was basically read-only, I disabled any sort of caching to prevent errors from "improper shutdowns" and disabled scandisk on boot, and used some winamp plugins to help keep track of what song was playing and its position, so that when i parked the car, it would basically start at the same place again when i got back in. I even had a website with what we'd now call a blog (i called it a build diary), but it's not online anywhere anymore, since i don't host my own website anymore, and space on the free blog sites is limited.