Driftwood can be found from many sources... depending on what you want and what kind of look you are going for.
Lights.. I really like the Odyssea T5 HO lights on my tanks (I have two set up with those lights) because they are slim and compact, relatively inexpensive for the light output, and my plants are absolutely flourishing with them.
This is one of the ones I have (I also have a shorter one for my 10 gallon, but the 24" will fit your 20 long): http://www.ebay.com/itm/T5-Dual-24-6...-/290726254580
(The Odyssea lights come with the bulbs too, usually whatever you can find in a retail store like Petsmart/Petco don't, which would add $30+ to your cost).
A lot of online reviews for the Odyssea lights say they get *really* hot, but I am convinced that those reviews either refer to the quad fixtures, or the longer ones - my 20 and 24 get fairly warm, but no more so than some of the single light T8's I've had... I can easily pick them up without waiting for them to cool off.
As far as filters.. that really depends on what you want. They all essentially do the same thing, the difference is only in the details - what kind of media that use and how easy it is to maintain them, and whether or not you wish to customize the filter media yourself (removing chemical filtration to add more bio filtration, for example). There's some argument that canister filters are better for planted tanks than a HOB filter because a HOB allows for more outgassing of CO2, so if a small canister (like a ZooMed 501 or Finnex 360) may be within your budget, that could be something to consider.