You could also look into one of the Coralife fixtures with two 18w T-5 bulbs in it. That would not be a huge amount of light (1.8 watts per gallon) but definitely better than the .75 you have now. I have two of those fixtures over my 29 gallon tank to get me to almost 2.5 watts per gallon.
It would be more light than the 2x13w and might be worth looking into if you want to find an option that doesn't require you to do any wiring yourself. If you have any questions about whether you would need to replace the plastic hood that came with your tank with a glass cover (cheaply available at the fish store, usually) to use their light fixtures safely, I would think that the Coralife customer service folks should be able to help you.