Installation Postgres 8.1.3 on Linux Suse 9.1

Hello list,

I've got a problem installing postgres on my Linux machine. The Linux
Version is Suse 9.1 and had a 7.4 postgres-version installed. Now I wanted
to update to 8.1.3 using the source files, when I run into the following
problem after using the ./configure - command.
The running of the script failed saying I have to get "readline" on my
system working. Well, "readline" is already installed, in Version 4.3. There
are new Versions out (5), but not for Suse 9.1. So I don't know what to do
now. I know that I can run the configure-script with the option
without-readline, but before I do so I would like to know what readline is
for and - if I run installation without readline -, what features won't work
on my database server.

So please list, make me a little smarter!
Thanks in advance,
Moritz