i'm starting to plan to build another reef tank. probably in the 29-46 gal range. this is the first tank i'm actually piecing together so i'm trying to make sure i'm getting what i need. we want to have sps in it, and some peaceful fish. these are my questions:

what is the difference between halogen and halide?
would halogen lights be suitable for a reef tank?
what spectrum is needed for corals, sps in particular?
is the halide really that much better than a t5?

we're redoing some lighting in our house so we've been browsing at lowes and found a lot of different light fixtures. they seem to be much cheaper than the metal halides you can get through a fish site or fish store, so i was curious what the difference was.