Your design is inspiring!
I've been collecting parts for the last few weeks and have search the Internet for the best looking construction... you win!
I started ripping out my radio this past weekend and fabricating the metal box to house the CarPC. I fully expect it all to fit inside the dash-board cavity created by making the same mods you've done to your car.
I'm using a Mini-ITX motherboard which is just about (within an 1/8") the same size as the 6-disk changer I'm removing. Aside from including a GPS, DVD burner, WiFi card, and a RadioShark, I'm installing an OBDII interface from http://obddiagnostics.com/
Thanks for plowing the way, now more may follow with much less effort.
Interested to see where your sticking the Traction/Defrost/Fog Light switches.