Old RH8 Kernel Uninstall Q

I've been using RHN to keep my errata updated. Very smartly, the kernel
updates preserve the previous kernels. Well, I'm starting to get a
collection of them and I'm sure the kernels are starting to hog
disk-space - or are they? Here's what I have:

rpm -q kernel
kernel-2.4.18-14
kernel-2.4.18-19.8.0
kernel-2.4.18-26.8.0

There's yet another update available that I've yet to download. Their
manual isn't clear on how to remove the old kernels and if the technique
automatically updates Grub or if I have to manually edit the config
file. Anyone mess with this?

Cheers,
Mike