I'm looking to do the same thing, Dano. Something like the Galaxy Tab would be perfect, but I'm not planning on spending that kind of money for a CarPC. Something eventually will come out and fit the bill. The only few issues I'd see with an Android based system is:
- Storage size: You're limited to a 32GB SDHC Card? It'd work for me, but maybe not you.
- Front End: Ideally I'd want a car-friendly front end. It really wouldn't be hard, as android already comes with a Car Panel type thing -- but just in case this isn't enough, I guess someone would have to code it.
- Power Control: Turning the system on and off with ignition. Might be a bit tougher than using existing controllers that are out there. Otherwise, you could always just wire a switched +12V (w/ dc/dc converter) for charging, and manually turn the system on and off each time.