Fedora Core 3 has reached End of Life officially with Fedora.
The Fedora Legacy Project still releases security patches and bug fixes due to community interest.

The instructions below show how to configure Feodra Core 3 to make use of the Fedora Legacy repository and reconfigure "up2date" for updating the system.

Note:

Instrucitons for Redhat 7.3 are also available here

Instrucitons for Redhat 9 are also available here

Instructions for Fedora Core 2 are available here

Instructions for Fedora Core 1 are available here

Add the Fedora legacy RPM GPG Key. 

# rpm --import http://www.fedoralegacy.org/FEDORA-LEGACY-GPG-KEY

Modify your sources file so that repositories are configured for Fedora legacy. Note, as of 23/3/06 the base channel at downloadload.fedoralegacy.org does not have any header directories, thus up2date crashes. This is why we have used an alternate repository (mirror.pacific.net.au) for the base channel.

# vi /etc/sysconfig/rhn/sources

change your repositories as below... 

yum fedora-core-3 http://mirror.pacific.net.au/linux/redhat/fedora/updates/3/i386/
yum updates-released-fc3 http://download.fedoralegacy.org/fedora/3/updates/i386/
yum fedora-legacy-utils http://download.fedoralegacy.org/fedora/3/legacy-utils/i386/

Save and quit vi.

Now configure yum anyway, incase you want to use it.

Download the following fedora legacy repo into /etc/yum.repos.d

Yum will now look at the right mirror sites.

Up2date will now work fine.