The controller board that the laser cutter came with is designed to connect to a PC with a parallel port. I planned from the outset to replace this. The board I chose to use instead is the EiBot Board, a derivative of the UBW (USB Bit Whacker) board. This board was designed by Brian Schmalz for the Egg-Bot, a little robot for plotting on eggs, lightbulbs, and other small round objects. It's available from Evil Mad Science and SparkFun.
My interest in it was as a stepper motor driver I could control via USB from any modern computer (it appears as a serial device, and it is controlled by sending it simple ASCII commands).