Definitely upgrade from RH9, since it is old and unsupported. (And wasn't that good when it was new
).
If you are comfortable with Redhat, then go with Fedora Core 5. It has a similar feeling, and most things are still in the same sort of places.
Alternatively, Ubuntu is an excellent distro. It is different from Redhat, but you should be able to pick it up quite quickly.
--Ian