I'm finally about to set up my very first car PC. However, I'd like to do it with some obsolete crap I have lying around at home. The goal for now is just MP3s & GPS. My technical skills are very high, as I've done other electical car-based projects, and I've got craploads of computer/mobiletech experience. However, I need some innovative ideas about the interface.

I'll go over my general plan first:
- The main PC will be a Xybernaut Mobile Assistant V in a dock (500MHz small form factor). It has one USB port & 1 PC card slot. It will probably run Windows 2000 or XP.
- An Audigy 2 PCMCIA card will go in the PC card slot, with a 3.5" cable to the aux in port on my JVC head unit.
- A 4-port hub will be connected to the USB hub. Connected to the hub will be: GPS receiver, external hard drive, wifi card.
- The PC will be mounted up front, under the radio cluster, so I can reach the power button (one touch suspend). I'd prefer an automatic power on/off, so any ideas here would be appreciated. Maybe there would be some way to use a small UPS... (?)
- The PC will be controlled by an Axim X5 w/wifi card mounted to a Proclip on the dashboard. The Axim will have a Remote Desktop session connected to the PC.
- All power cables will be run to an extension cord connected to an inverter mounted under the seat (or in the glovebox). There will be a master power switch up front, so I can turn everything completely off when I'm not driving the vehicle for a long time.

The Axim is just there as a touchscreen for the PC. However, the main challenge is cramming an MP3/GPS interface onto a 3.5" 240x320 screen. Any ideas on how to make the interface easily usable would be GREATLY appreciated.

I know there are lots of different interfaces for car PCs, but I'd prefer a free one for this build. If there's anything you can think of that will scale to the small Axim screen, I'm all ears. Also, if you see any way I could make the design more efficient, I'd love to hear it. Keep in mind that my ultimate goal for this project was not to have to buy any new stuff.