You should take a look at the Infill T3
http://store.mp3car.com/ProductDetai...Code=SDK%2D007 It addresses all these issues and is a huge leap forward in terms of ease of installation and getting things to work as they should the first time out.
The display is digital, does native 800x480, automatically dims when you put your head lights on, and is sunlight readable.
The power supply supports hibernate, standby, and powering off well. It will even kill the power automatically if it detects low voltage. Return from standby is under 5 seconds.
The windows XP operating system isn't meant to be used while driving. StreetDeck runs while in motion and hides all the usability issues of standard windows, you can use windows however you want when stopped.
The Infill has a built in amp and all components were made from the ground up to work in the car. Ground loops shouldn't be an issue on typical installs.
The Infill runs StreetDeck, which will get you all the features and more of what you find in most in car nav systems.
The cost is certainly more then what you will pay if you cobble together a system yourself from various home pc parts, but there are a lot of custom parts in the infill made exclusivly for use in the car pc and the system is competive with similar all-in-one non-pc head units, plus it gives the expandability and customizability of a typical computer.