T5's work best on shallower tanks (less than 20-24 inches deep) and the deeper it gets, the less light penetrates to the bottom. If you did get a T5 HO
SLR fixture or retro (I believe Melosu is refering to) then on a tank like yours (which is about 30'' deep) you would basically have to keep most of you corals in the top half of the aquarium.
If you got a 400 watt metal halide you can keep softies and lps
corals on the sand and near the middle then place sps
near the top.
You can get a good 400 watt MH
retro for around $300-350.
A T5 fixture would cost you about the same, but the operating costs and heat would be less and the light will not penetrate as deep.
The fixtures you are looking at are (not trying to be rude or anything) cheap and you will only want to upgrade once you get more experience and see how limited you are.