I have housed all the control electronics in an old PC case. The stepper motors are controlled by three motion control products MSD542 microstepping drivers . These are bipolar current chopping drivers. The driver is optically isolated from the input signals. Suppling power to the drivers are two PS 407 non regulated switch mode power supplies wired in parallel (again from motion control products).
The motor cable is Oflex classic 115-CY, a shielded flexible control cable made by Lapp Cable. This is not really designed for continuously flexing applications, but I bought a big roll of this stuff off e-bay for around £20 so I can replace it once in a while. I originally used 5 pin DIN connectors to connect the motors to the drivers, but these were not really suitable for wires (or currents) of this size. I ended up using Molex 6-way panel mounted connectors.
The input signal from the parallel port of the computer goes to a C10 bidirectional breakout board from CNC4PC , which takes its 5V power supply from a USB cable connected to the computer. There is also an emergency stop button, and limit switches which both have yet to be connected to the C10 board. The E-stop button is not in the best place, so I am going to move it to the CNC machine itself, to an easily accessible place (Health and Safety!).
I haven't put a cooling fan in the case yet, but the options are a mains voltage AC fan connected to the mains supply or a few DC fans in series connected to the switchmode power supplies.
The computer controlling the machine is an old Compaq which used to be my server, running for weeks on end with no problems. I am using the free program EMC2 (Enhanced Machine Controller 2) to control the machine. Installation was a breeze using their Ubuntu live CD.