Resurrecting this thread, I finally got around to upgrading the lighting rig to LED bulbs, and man! I'm loving it. I got some 4W MR16 bulbs from Deal Extreme, and I've got 2 of them mounted now. They are bright enough to where they will temporarily blind you if they're pointed right at your eyes at night. However, they give excellent ground coverage, and were only $10 for each bulb.

Here's a closeup of the lights themselves. I had to modify the housings to accept the longer LED bulbs.