You can use the iso's to upgrade your current version of RH9 to the Fedora Core Project. They have instructions over at www.fedora.redhat.com
that should help you. It appears to keep your existing data untouched and only upgrade the necessary files to move to the Fedora distro.
Let us know how it goes if you decide to upgrade as I'm on the fence right now since my RH9 is working wonderfully.