(the guy at the pet shop said it was pretty good light)
HEHE, He must be like a vampire or something then.
With a tank of the shape you describe you need more light per gal
than a tank of the same capacity that is shorter. The light you have will be ok for the fish. The live rock will strugle along but you should not expect to see any growth in the way of macro algae and even the coraline growth might be stunted at 1/2W per gal
of light output.
Remember this is your tank so if you feel you dont have the right lighting then look for a lighting setup that makes you feel better about your tank. I personally would suggest maybe a pair of 55W Power compacts over the tank.
That would give you substantly more light and also would probably bring the colors of the rock and the fish out much more than the current 14W florecent.