Telion,
Hats off to you sir
. Since you obvioulsy spent a great deal of time and effort (which IMO is worth much more than the cost of the equipment), you may want to make the setup modular.
With summer in-car temps that can reach close to 200 degrees, any major component can fry (i.e. ram, sysboard, or HD) so you may want to make them easily removable...
Also, you may want to consider this as an auxilliary setup, so if the 'PC' is removed you will still have radio/cd/ipod etc. Just use a HU that has multiple aux input(s) to the TFT.
I have a vison for a similar setup- only that it will utilize a docking station for my laptop.
Im always down to brainstorm/troubleshoot if you reach a hurdle...
-Steve