[CentOS] crypto, readline and zlib libraries - Postgres install

I have the 5.x Centos DVD and loaded it.

Please be gentle with me, as I'm nominally a FreeBSD kind of guy... :)

Anyway, I'm trying to install Postgres and the three libraries in the subject line are missing off the base installation. I figured out how to load gcc using yum, but those libraries aren't there, and I need the former in particular in order to enable SSL for Postgres client connections. A perusal of "yum list" with an appropriate grep or two doesn't elicit anything useful.

Anyone know where I find these? I loaded just the standard distro, no graphical user environment (neither Gnome or KDB)

Thanks in advance.