OMG, this is something I *actually* have experience with!

Okay, *cracks knuckles*...

The first thing you want to do, it drill 4 2" holes and one 3" hole in the floor of the cabinet. Attached is the pattern of mine.

Then, you get some BLACK, 2" 90-degree pvc plumbing joints- You connect the 2 joints to make allow incoming air and it makes a light trap. Also, get two 3" 90 degree plumbing joints. This allows you to run power cords into the cabinet and provides some ancilliary air flow.

On the roof of the cabinet, drill a 4" hole and get a 4" sheet metal duct connector. It's about 5-6" long. this will be your exhaust.

As far as moving air through the cabinet, a 265 fan is what I have and it works great!

I also use an air-cooled, glass-enclosed hood, and I have the blower run air through the hood, into the fan and out the exhaust hole. It works great!

A note of caution about 400W lamps and the C13: If you want your fan hanging from the inside of the cabinet, make sure your hood and fan can be level with each other. My hood takes up the entire area of the cabinet, so I must move the fanoutside the cabinet when the hood needs raised to its max height. It looks crappy, but still gets the job done.

Here's an optional thing for you as well: get a plastic sheet and cut it so it lays on the floor of your cabinet. Then, cut holes in the sheet to allow air flow. This will protect the wood from water.

When you build the C13, make sure you get a sheet of plywood and attach it to the back of the cabinet. If you just try to use the included backing, it's too flimsy and the cabinet won't be strong enought to hang the light and fan.

You have a great start. Now, all you have to do is put the finishing touches on it.

Good luck!