install new version of Redhat without deleting /var/lib/pgsql ? Is it enough ?

Hello erverybody,
I need to install a new version of Redhat on my server.
On the distro, pgsql data are in : /var/lib/pgsql (which is mounted on
its own partition).
Can I "just" install the new version of Redhat, reinstall the same
version of Postgresql (7.4.8) ?
I'll do a pgdump all just in case

Thanks !