When I clean installed everything on my G5 tower, I never thought of popping in the Airport CD that came with it. Airport is running fine right now. What exactly does the Airport CD install that isn't installed with the OS?
The Aiport CD does have one or two extra tools (which you can also find on the Apple web site). Depending on which models of Airport you have (e.g. version of the base station or Express), you can have (latest version):
Many of the functions are redundant but some provide access to some deeper controls.
It does pay to tune your Airport network and to use the most appropriate security levels. Many of the advanced Airport Extreme/Express functions (e.g. AirTunes) need tweaking if you have a mixed network). For example, my home network is set up so I can print wirelessly or through ethernet to an always-on, standalone printer, send Airtunes either from wireless or wired computers to two different stereos and everything is protected (unlike at least two neighbours....).