Right, nice and slow. I about went in sane when several people recommended 4 fish for my 72 gallon aquarium. If you were planning on owning tangs, then you might have a problem. This is one of the variables the book discuesses. However, if you want 2 percula clownfish, and 2 green damsels - no problem.
I've found in my freshwater experiences that if you have a large medium (biowheels in my case) on which these nitrifying bacteria can live and you add fish slowly, Ammonia and Nitrite are not a problem reguardless of the number of fish. Thus, the only element you should concern yourself with is Nitrate. Of course there are several ways of dealing with Nitrate - 1. For Freshwater, live plants work very efficiently, 2. For Saltwater, protien skimmer work well, and 3. for both Freshwater and Saltwater, a 10% water change once every one to two weeks. Just make sure Nitrate stays below 20ppm, perhaps 10ppm for coral reef.