I had the same problem with the "Add/Remove Programs" recognising CD's
Sometimes it works okay...other times it says it needs disk 'x'...when the disk is in the cd-rom !!! Strangely enough it sometimes works after a re-boot - I guess something is not being unloaded/refreshed but I don't know what. Re-starting X (ctrl-alt-backspace) doesn't make any difference.
It's possible to copy the files from the CD, and install manually with RPM.
"Synaptic" seems to work quite well...to be honest I still get confused with RPM / yum etc.
