aaltonen.us » Blog Archive » Yum in Fedora Core 3 is the best explanation of how to use yum on RedHat Fedora 3. Although I found the RPM-GPG-KEY-fedora file in /usr/share/doc/fedora-release-3/RPM-GPG-KEY-fedora, not /usr/share/rhn/RPM-GPG-KEY-fedora.
Go to http://www.oreilly.com/catalog/samba2/book/toc.html for the complete text of O'Reilly's definitive book, Using Samba, 2nd Edition By Jay Ts, Robert Eckstein, and David Collier-Brown (2nd Edition, February 2003)