erroneous dependency errors while using Package Manager

I am unable to install the KDE desktop environment via
the add/remove packages Package Management application
(/usr/bin/system-config-packages) on Fedora Core 3.

I am running Fedora Core 3 kernel release
2.6.12-1.1378_FC3smp.

After checking the KDE box on the Add/Remove packages
window, and clicking the "Update" button, "preparing
system update" dialog window appears, followed by a
window with message:

"Package Not Found

The following package could not be found on your
system.  Installation cannot continue until it is
installed.

However, the most recent version of the library is
installed, according to yum:

$ yum list | grep "xorg-x11-libs"

Any ideas what might be going wrong here?

Thanks,
-Andrew Stewart