Here's the script I'd run manually every time I upgraded my kernel:
#!/bin/bash
cd /
mv vmlinuz vmlinuz.old mv initrd initrd.old
NEW_KERNEL=`rpm -q kernel | tail -1 | sed -e 's/kernel-//'` ln -s boot/vmlinuz-$NEW_KERNEL vmlinuz ln -s boot/initramfs-$NEW_KERNEL.img initrd
exit 0