If you're serious, then get a serious light. If you just want to fart around, then get a light with only 2 bulbs in it. Personally, I'd go with AT LEAST 6 bulbs.
I have (6) 24w bulbs over a 30Tall and I wish I had 8 bulbs.
Depends on what you want to do with the tank. Decide what kind of corals you like. Do you like lower light zoas, polyps, mushrooms and LPS? Or do you want to grow SPS and clams?