I'd use up2date, but there always seems to be some additional packages to update that yum finds which up2date doesn't.
Here is the relevant output from yum. What you see on the last line is symptomatic of the hang. It doesn't always hang at the same "%", but it always hangs on that file:
# yum update
Gathering header information file(s) from server(s)
Server: Fedora Core 1 - i386 - Base
Server: Fedora Supplemental Packages (Stable)
Server: Fedora Supplemental Packages (Testing)
Server: Fedora Supplemental Packages (Unstable)
Server: Fedora Compatible Packages (stable)
Server: Fedora Compatible Packages (testing)
Server: Fedora Compatible Packages (unstable)
Server: Fedora Core 1 - i386 - Released Updates
Finding updated packages
Downloading needed headers
Damaged Header /var/cache/yum/updates-released/headers/kernel-source-0-2.4.22-1.2135.nptl.i386.hdr
getting /var/cache/yum/updates-released/headers/kernel-source-0-2.4.22-1.2135.nptl.i386.hdr
kernel-source-0-2.4.22-1. 12% |=== | 48 kB 00:20 ETA
-- Clint <clint@xxxxxxxxxxxxxxxxxxxx>