Intallation of postgres 9.0.3 gives an error on already installed postgres 8.4 on the same machine

I have postgres 8.4 already installed on my machine

Now I am trying to install 9.0.3 on the same machine

But when I am trying to run this particular rpm i.e postgresql90-9.0.3-1PGDG.rhel5.x86_64.rpm

rpm -ivh  postgresql90-9.0.3-1PGDG.rhel5.x86_64.rpm        it gives me the following error:

error: Failed dependencies:

        postgresql < 7.4 conflicts with postgresql-server-8.4.6-1PGDG.rhel5.x86_64

Can anyone help me with this error.

Thanks