Error installing PostgreSQL

Hello:

My first try installing PostgreSQL (CentOS 5.2). I am following the
"Installing PostgreSQL on Red Hat Enterprise LINUX / Fedora Core". This
document says that to install a PostgreSQL Server, I need to install
(minimum) the following:

1. postgresql-libs
2. postgresql
3. postgresql-server

When I try to install:  postgresql-libs-8.3.7-1PGDG.rhel5.i386.rpm
I get a dependency error saying that file:  libpg.so.4 is missing.

Question:

1. How to fix this problem?
2. I noticed that "postgresql" module also need libpg.so.5. How this can
be fixed?

I have searched the net and there is lot of quires about missing
libpg.so.4 but no solution.
HELP.

Sam