Recently went from RH 9.0 to FC3. During installation it asked for a RHEL "extras" disk, which I didn't have or know what it was talking about. Installation went apparently fine. However, when I try to install mozilla 1.7.5, It doesn't seem to do this properly, either the installer version or the tar.gz file. The files get extracted, but going to the executable does not get it going. The mozilla site says it needs Xfree86 or equivalents. so I thought it should work with the X.org system. Am I wrong, or did I miss something in installation? I understand that FC3 should be updated right away.

Sounds like you are trying to install from source
Why can't you use yum ?