Any live distro will do. For example, if Red Hat 9 boots a fully working OS from the CD (and then gives you the option to install to the hard drive) then that will do as a rescue disc. In fact, even if that's not the case, there's a good chance that you can use it to reinstall GRUB/LILO.
What options (if any) does it give you when you boot off the CD? Also, do you use GRUB or LILO?