The lighting depends on the tank dimensions. If it is less than 24" in height, I have been told the T5 flourescent are fine. If the tank is taller, you will need MH. Also, a good rule of thumb is 4-5 watts per gallon. So, a 125 gallon aquarium should have at least 600-725 watts of lighting to grow corals, less if it is fish with live rock only.
Mike