As mentioned I put the Dvd player in the center console. I also have the Creative Live! External in there:
I put the PC under the passenger front seat. It fits perfect with plenty of room for peoples feet in the back seat :
Here is a pic of the back seat area when the front seat is where it stays and the PC is where it stays.
I also have 2 - 9" Headrest monitors that can play what is playing in the front or anything else the backseat passengers want :
Right now they are running off composite but I have 2 - Vga controllers ordered for higher resolution. the 9" can display 800x480.
And here is a pic of RoadRunner running :
