Wattage isnt everything in this case. T5 are more intense and will penetrate the water greater than T8's will. The set would be fine for quite a few corals. Others will have better responses. My tank has a total of 5.8watts per gallon.
Moved to General Hardware and equipment discussion. I agree with Justin as far as intensity. WPG is a very broad rule that has become quite outdated but it`s sometimes easier to convey to newbies than intensity or par.
Well i went with that 156w 36" t-5. I think is should be a huge upgrade from my 24" 65w under canopy coralife pc. My tank dimensions are 36x12x24-high. So its a tall 45 gallon, but i feel the lighting should be perfect.
Generally since you have recently ordered it; it should be a new ballast. You shouldn't have to worry in my opinion. If the catching fire was a common problem it would have been fixed and never used the old again.