OurSam - if you're using a 20 long right now, I would suggest the Reptisun 10.0. It is the best fluorescent tube you can get. The MVB gives off a little to much to use for a 20 gallon tank. They're about $40 or so at the pet store, but if you shop on PetMountain.com they usually have deals along with cheaper prices than at the pet store.
As for heat, I'd just play around with some household bulbs until you get the correct temperature. If you get a floodlight, you can get a lower wattage with more heat.. energy efficient if you will. Since you have smaller tank I would start with a 75w maybe. Do you use anything to check your temperatures? That's really important. In order for a dragon to properly digest their food, the basking temperatures need to be between 105-110 for younger dragons and the cool side of the tank in the mid- to high 70's. The thermometer I would suggest would either be a digital thermometer with a wire probe (you can get one at wal-mart for $12 and it will measure both the cool and hot side at the same time) or a temperature gun. In order to get a proper reading on a digital thermometer, you need to set it directly on the basking surface (log, hammock, rock.. whatever it may be) and leave it there for 45 minutes.
If you have any other questions, feel free to ask.