You've already stated that you didn't want to build another computer, but I'm doing exactly as you want to do now in an Acura Integra using a Via Epia Mainboard in a Casetronics case (mounted in glove box) running Windows XP. The touchscreen is a T View (which was cheaper and works better than the lilliput I also had) and is mounted in dash in a retractable housing gotten from www.digitalww.com. This elminates the need for a mouse. I'm running Frodoplayer as the main front end and I have Empegface running on top of the front end to keep track of the Empeg stuff as I cannot see the Empeg screen when the touchscreen is out. I've just simply run a crossover cable to the PC. I am also controlling XM radio from the touchscreen and the sound from the PC is run into the Aux In on the empeg. The GPS software I'm using is Destinator but have recently got Iguidance but havne't installed it yet. I had Mappoint but was not happy with it. I've been very happy with Destinator. The Frodoplayer software has an on screen keyboard that can be accessed at most any time. This makes it easy to enter in addresses for GPS routing and doing searches. Obviously this is all for Windows software but you may want to rethink your plan as there do not seem to be the software resources available for Mac to do what you're wanting. Although there are some listed at www.mp3car.com.