Wow, lots of interest in this. Ok, I did up a quick page with a more detailed overview of the system:

XPterra Carputer

To answer some of the questions directly:

The map software is Delorme Street Atlas Deluxe. It's not perfect, but it works well enough. About three more versions and they'll have it right. I have Mapsource but haven't tried it in the car yet, I would like to get some topographic maps too eventually.

The player software is Media Jukebox 8 Beta. I like it for the library management features mostly, plus it will play MPC files, which is the format all of my music is in. I am waiting to try Winamp3 once it's final, and also looking forward to Sonique2 when it's released.

The sound is routed to the aux-in on a Blaupunkt head unit, not the best but it sounds ok. I have a slight noise problem (ground loop) that I haven't been able to filter out, so I need to redo the power wiring for the PC.

Voice control would be cool, I hope to try that out someday. For now I use a small trackball mouse, IR keyboard (check eBay for mini keyboard), plus the touchscreen. A wireless NIC would be good too, but for now I have a long Cat5 that I run out to the driveway for online updates and such. The hard drive is removable so I can just plug it in to my home computer to transfer files.

Power is a Keypower 250W DC-DC. I started with an inverter but quickly decided the money for a good power supply was worth it. More info on the overview page.

The PC enclosure is semi-custom, more info on the overview page. It doesn't have a powered cupholder though.

The best place to learn about doing something like this is the MP3Car Forum . Those guys have tried just about everything, and they have a lot of experience and talent over there. There are a lot of different ways to do things.

The whole project was pretty involved, but I probably made things more complicated then necessary. I'm glad it's mostly finished, my play money and time is devoted to more important things now, like torsion bars, lights, and a winch.

Thanks for the comments!

Tim