I have stripped out all of the PC guts and I'm left with a USB card reader, power button, rotary encoder and some control buttons, front USB and FireWire ports, a place for a DVD drive, a gap and mounting plate for the 7-in display, two double three and a half inch hard drive bays with fans, and plenty of space for the RF side of things.
I have to come up with some way of securely mounting the RPi behind the display and between the two hard drive bays, thus giving plenty of air flow and easy access to all the peripherals at the front of the case, and then some way to secure the remainder of equipment in the back of the case. Hopefully this will come out as a functional and nice looking as it is in my head already