THIS site offers so really nice options for upgrading your lighting to compact power flourescents. I have not done this myself, yet. If I ever do decide to get compact flourescents then this is where I will go.
Remember, when you are figuring your lighting, CPF are equivelant to 1.35x the light of normal output flourescents. In other words, if you have 10 watts of CPF then it is equivelant to 13.5 watts for calculations.
Follow the guidelines from
HERE . Scroll down and input the dimensions of your tank to get an idea of what amount of lighting you need to reach the basic levels. This is only a guideline but it has been proven by many to work for both the beginner and the expert.
As my signature implies, all tanks are different. I have 2 tanks side by side under the same light fixture and can not grow the same plants in both of them. Different things will work for you but this is a good place to start.
And remember, pateince, patience and then a little more patience when you are about to give in. It will happen but you have to make it happen unless you are one of the very lucky ones, unlike me. ;)