There are three 12-volt lamps in the cabinet (two behind the coin door and one underneath the translucent trackball), and one florescent lamp behind the marquee. To get power up to the coin door and trackball lamps, I just have a separate AT power supply sitting on a shelf in the cabinet, with "hot" and "ground" wires going up to the lamps. For the marquee lighting, I'm using a standard flourescent light.
You can see the 12v leads spliced and running up the right side to the coin doors and the trackball.
The lights are just little 12 volt lamps, so you've got to figure out how to get 12 volts up to the lamps. There are a few ways that you could do this, but I figured that the easiest way would be to splice up a couple of wires from a regular AT-style PC power supply. If you look at the molex-style connectors on a PC power supply (the connectors that you would plug into your hard drive, floppy drive, CD-ROM, fans, etc.), you'll see it has four wires: one yellow, two black, and one red. The red/black pair is 5V, and the yellow/black pair is 12V (the black wires are the grounds, by the way). So, in order to get a 12V pair up to my lights, I just spliced the yellow/black pair up to my coin door lights. I used cap-screw connectors where the wires splice, since there is actual electricity running through there (albiet a small amount).
There are two little prongs on the backs of the lamp assemblies for the 12V leads, which is where you actually connect the wires. These lights don't have any polarity, so it doesn't matter which prong you have the "hot" wire hooked up to and which prong you have the "ground" wire hooked up to, as long as each prong has one of them connected to it.
The lights will light up as soon as there is electricity going to the PC power supply that's feeding up to them. I'm using an AT power supply which has a maintained switch, as opposed to an ATX power supply which has a momentary switch. Quick explanation:
So since the lights are powered by a maintained switch, they are always in the "on" position. As soon as I turn on the main power to the cabinet, the lights will come on.
As I said, I have a separate AT power supply on a shelf in the cabinet that's feeding power to the coin door lights and the trackball light. Why didn't I just try to splice off of the power supply that the PC is using?
For lighting the marquee I just have a standard run-of-the-mill $15 florescent lamp that I got at the local hardware store mounted in there. The only thing worth noting about the lamp is that it has a white plastic cover in front of the bulb to diffuse the light. It actually works out really well for lighting the marquee nice and evenly.