Upgrading from 7.2.1 to 7.2.3 on RH7.3

Suffice to say I havent a clue on what I am doing.

I am trying to upgrade to 7.2.3 using downloaded RPM's. The installation for 7.2.1 went quite well, but I cannot
upgrade.Here is what happens: 

[root@DOC root]# rpm -U postgresql-libs-7.2.3-1PGDG.i386.rpm
error: failed dependencies:
        postgresql-libs = 7.2.1 is needed by postgresql-7.2.1-4
        postgresql-libs = 7.2.1 is needed by postgresql-server-7.2.1-4
        postgresql-libs = 7.2.1 is needed by postgresql-devel-7.2.1-4

Okay, so lets just try to remove the existing application:

[root@DOC root]# rpm -e postgresql-7.2.1-4.i386.rpm
error: package postgresql-7.2.1-4.i386.rpm is not installed
[root@DOC root]# rpm -e postgresql-libs-7.2.1-4.i386.rpm
error: package postgresql-libs-7.2.1-4.i386.rpm is not installed

I am confused, or maybe even worse.

thanks in advance,

ben