yumEX is basically garbage
to Upgrade CentOS 5.3 to the current 5.9 ( soon to be 5.10 ) for the OLD 5 series
yum --releasever=5.9 upgrade
BUT third party repos WILL CAUSE CONFLICTS, with an almost 100% certainty !!!
the third party repos for 5 are almost all incompatible with each other
and in your error the "rf" on the package name means "RpmForge"
and rpmforge for 5 is incompatible with -- well EVERYONE ELSE including centOS5 -update and CentOS5-base repos
uninstall EVERY "rf" package first
then upgrade ( as per above )
to get a list of installed rpmforge packages
rpm -qa | grep rf
--- output a text file list ---
rpm -qa | grep rf > /RpmForgeList.txt