I'm finishing up my first grow soon I think. I have a 2'x3'x4' CFL cabinet. I don't plan on upgrading the lights for my second grow. Yeah, I'm flowering under 6x26W. I know I could do better with better. I have one small LST plant. It works.
But I really think the trick is to get as much of the plant as close to the actual surface of a fluorescent bulb as possible. I've tried to keep my plant flat under a bunch of spread out bulbs. I'm trying two plants and might even scrog for my second grow, and can add more bulbs across the top as needed.
When you consider the limitations of florescent, there are better ways to get bang for that many watts in a single light unit. All is not lost, though. You're lights will work. Just don't expect the biggest yields. Take the time to learn to use what you got and learn to grow.