I practice law and recently finished replacing all the code in my office with FOSS. It took over 5 years, and my brother had to help me a lot. Here is what I'm running now:
* Ubuntu 7.04
Drop me an email some time if you are interested in talking FOSS in the context of small offices.
I'm also looking for a technical consultant who uses FOSS but also has experience with small professional offices and/or bookkeeping.