What makes a light fixture 12v DC vs. 120v AC?

Naio wrote:
I avoid florescents like the plague on AC, too :B

Smart. They're pricey when they start to go out. Probably DC ballasts cause a lot of the problems themselves, AC might last longer due to stable AC. But still, going the way of the dinosaur perhaps, as far as I know.

You can get the (can't remember what they're called) newer type efficient AC bulbs (look like a flexible straw bent up) and they're really nice and very efficient.