I have enabled centosplus. When running update this is the error that appears
error: unpacking of archive failed on file /boot/System.map-2.6.9-67.0.7.plus.c4 smp;47f20105: cpio: write
Opps.. walked you into that one

Best to only have the 5 standard repos enabled for a successful update. The wiki should have them listed.
That said, the kernel should install 'correctly'.
At the end of the day your kernel modules have to match your kernel.
For example.... a bad example...
[root@tiger ~]# uname -r
2.6.9-67.0.1.ELsmp
[root@tiger ~]# rpm -qa | grep kmod
kmod-slip-1.0-2.2.6.9_67.0.4.EL
kmod-appletalk-smp-1.0-2.2.6.9_67.0.4.EL
kmod-ppp-1.0.2-2.2.6.9_67.0.4.EL
kmod-ppp-smp-1.0.2-2.2.6.9_67.0.4.EL
kmod-slip-smp-1.0-2.2.6.9_67.0.4.EL
kmod-appletalk-1.0-2.2.6.9_67.0.4.EL
[root@tiger ~]#