IN Car PC

I mentioned this in another thread but thought I'd bring it out into the open for general discussion.

I'm thinking of building an in car PC for mine. as I have a pre facelift car I'll be looking to mount a touchscreen somewhere suitable unless its a dead easy and not silly price to upgrade to the later console and embed a screen into that.

My initial idea is to use one of the latest Netbooks as the base and run something like MythTV as a media centre app. I'm thinking of fitting a second screen in the back for my daughter so I can enable video etc with a headphone socket for audio( in this case maybe keeping the original stereo and wiring it such that the headphoen socket could be isolated so I can listen to the radio whilst she watches videos etc)

Anyone (apart from Ian who responded in the other thread) done anything similar?