Kernel Recompile

So, after 5 years of using linux, I've finally decided I'm ready to do a kernel recompile. I started playing with one at work on a test box, and I hosed it. No big deal, I expected it. What I'm wondering is, how can I make a copy of the old kernel, and make an entry in grub for it, so if I hose it, I can just boot to the known working kernel?

Thanks
Jim