also before you go to far
CentOS 5.9 is UNSUPPORTED !!!
and the old 5.9 repos have been moved to the historical archive " The Vault"
if you MUST as in 100% must use the OLDER 5 series then upgrade to the ONLY supported version in the legacy 5 series
this is fairly easy to do
yum --releasever=5.10 upgrade
mind you 5.10 is the VERY LAST minor upgrade that 5 will ever get
if the old legacy 5 is NOT a 100% must use
then install the current version