Well, you've got a storage backend, an interface component but your a/v solution seems to be missing the A.

Even once you've solved that you'll still be left with a PDA for input, which just doesn't work very well. It needs to be charged constantly, so it'll have to be in a cradle, which rarely look good suction cupped to the windshield. At that point, you've got four buttons and a touch screen for your UI. The touchscreen while driving can be used for maybe four buttons, but at least they could be dynamicaly labled.

Camelot was the next generation in car solution, it's a pitty it didn't make it any further than it did.

Matthew