Gnome (or KDE) upgrades are not easy to do on older distros (and redhat 9 is now an older distro with no official redhat support). There are many dependancies to install ... hundreds of files.
I have Gnome 2.8 running on
Gentoo Linux and on
Ubuntu Linux currently.
I didn't see any Gnome 2.8 rpms for redhat 9, but there are some for Fedora Core 2 here:
http://people.ecsc.co.uk/~matt/repository.html#apt---------------
You can tell what version of gnome you are running with the command:
rpm -qa | grep gnome-desktop