Hi Mjc
Reefkeeping is one of those hobbies where, if you ask 3 people something you'll get 5 opinions.

Lighting has SO many variables. It depends on what you want to keep, and the size and depth of your tank, what colour you like the light to be, how much you want to spend, ongoing and maintenance costs, and the position of the Moon in March. Deeper tanks need stronger lighting. Led are pricy but have no maintenance costs and don't use much electricty. T5 aren't quite up to SPS unless you get 6 bulb fixtures but you can have just about everything else. You need to replace bulbs every 6-8 months though, and they can be 10-20$ each. CF aren't as good as T5, but you can keep LPS. Bulbs are difficult to get, depending on the hood, and pricy unless you use household twisty bulbs, which probably isn't great on a reef but works well for houseplants. (I have CF lights) T8 are cheap, restrict you to softies, and you probably should replace the bulbs often.
If you're on a budget may I strongly suggest NOT trying sps? I'm a noob myself, and in fact my tank is very similar to yours; roughly 18" deep and wide. I'm keeping LPS- and I need to seriously upgrade my lighting to make them happy. (I have 105 watt compact fluorescents. It's an old fixture). LPS generally require less light than sps but are sort of edging into the care regime.
I'd go with something like:
http://http://www.ebay.com/itm/T5-Q...194?pt=LH_DefaultDomain_0&hash=item19dfa64cc2
I'm researching led myself.
I can tell you that everybody seems to like the 300$ Kessils. *g* PAR38 bulbs are 80$ish US and fit into a normal light socket.
Well that turned into a novel!
hope that helps a bit
ivy