What light are you going to use? I have one of these tanks myself and I am still trying to figure out what light to use.
I am using an Aquasun 36" T-5HO fixture from Petco. They are good lights for the price. I have had one over my 36g for the past couple years and It has worked perfectly. It has a single reflector, so there is a little lower par than similar lights with independent reflectors, but I can get the perfect light level out of my 21" tall tank.
It comes with suspension cables which are a nice touch so I can adjust the light level as needed