The procedure for this upgrade follows the same steps outlined in: RedHat Fedora: Fedora Core 1 to Fedora Core 2 Upgrade with the exception of the below step.  If you have not already upgraded to FC3 please visit RedHat Fedora: Fedora Core 2 to Fedora Core 3 upgrade. page first before going up to FC4.

You will only need to replace step #8 with the below step: 8 ) Install fedora-relese either using http://download.fedora.redhat.com/pub/fedora/linux/core/4/i386/os/Fedora/RPMS/fedora-release-4-2.noarch.rpm or http://fedora.osmirror.nl/core/4/ppc/os/Fedora/RPMS/fedora-release-4-2.noarch.rpm or use another mirror from the fedora.redhat.com site. For more legacy mirrors, use the instructions on the Fedora Core 1 to Fedora Core 2 upgrade above.

BASIC STEPS

1. nice -n 19 yum update
2. cd /some/dir
3. mkdir ./F3toF4
4. cd ./F3toF4
5. Ensure you have debuglevel=10 and errorlevel=10 enabled in /etc/yum.conf in case we need more debugging information.
6. nice -n 19 yum -y upgrade
7. nice -n 19 yum clean all
8. nice -n 19 yum clean all (Just to make sure)
9. wget fedora-release-<ONE OF THE ABOVE LEGACY MIRRORS>-notes…..
10. wget fedora-release-<ONE OF THE ABOVE LEGACY MIRRORS>-…..
11. rpm -Uvh fedora-release*.rpm
12. cat /etc/fedora-release  (Make sure number 4 appears in the release)
13. nice -n 19 yum -y upgrade 2>&1|tee ./F3-to-F4-upgrade.Dec.5.2006.02.10.PM.txt
14. Refer below for any issues and repeat step 12) as necessary.

You can also use the mirrors from fedoralegacy.org if your distribution is too old since most old RPM's will be moved out of the fedora project sites by now due to their old age.   The fact that you would have to upgrade using outdated RPM's would be the biggest hurdle for you from this version.  Again, the first upgrade steps other then the differences above, still apply to this upgrade.  Once done, you can proceed to the Fedora Core 5 upgrade.