new book, new tank?

So, I picked up Joyce Wilkerson's book on Clownfish at the library last week. It is a great book. I have generally shy-ed away from books on fish stuff because a lot of it seems out of date compared to finding stuff on the daily (hourly) updated forums out there. But, this book is awesome. It has a ton of great info in it.   Some of it is out of date, but as a whole, the book rocks!!
Anyway, since moving into my house about a year ago, I have been in the planning, researching, dreaming (read: too poor to buy the tank I want) phase of my next reef tank and unfortunately have to get my fix by pictures.   But after reading this book, I am thinking of starting a non drilled/non reef (okay maybe some softies) tank that houses a pair of clowns.   I am thinking 20 gal long (have one that used to be a sump in the basement) with a hob filter (charcoal and GFO) and a couple of koralia powerheads. Nothing fancy, probably just cfl bulbs to start with, some rock, sand and a cuc.   
anyone have a basic tank like this? any thoughts or tips on how to proceed? My only other saltwater tanks have been reefs with more elaborate filtration, but this seems easy and cheap.   
Thanks for any info you can pass along.
PJ

Do you use ro water or just tap water in these systems?

pgravis wrote: Do you use ro water or just tap water in these systems?