Thanks to people like Diezel who posted the original article on nixadmins.net, we now know that in order for Firefox 2.0 to run on a CentOS (or Red Hat EL) version 5.1 machine, we need to install compat-libstdc++-33.
Using yum this is done as easy as entering
#yum install compat-libstdc++-33
s the root user. The rest is trivial.