Really, lighting in the correct spectrum is what you need most. Depending on what plants you want to grow you may need to upgrade, you may not.
I too started out with Aqueon lights on my 28. The single tube t-8 did fairly well for me, I could grow a ton of low-light plants, but anything that needed moderate to high lighting would end up melting.
You'll want to find flourescent, power compact, or compact flourescent lighting in the 5,000-8,000 kelvin range. The rating should be on any flourescent type light you find.
What is the current lighting on the tank? It might work or you may have to upgrade, you may need to find a stronger bulb or ballast for it too.
After you figure out if your current lighting will work or not, you can decide on plants. I'd suggest starting with low light plants because most can take a beating