Setup grub as the boot loader in your MBR

# Boot from CD and choose linux rescue which will mount the system.
# Write to the MBR. Assuming grub.conf is intact, continue with the process. Type "grub" (return) to enter the grub shell.

Tell grub where to find the requisite files. If you know where they are, enter something like:

root (hd0,1)

(hd0,1) means primary controller master, second partition. If you DON'T know where they are, type:

find /boot/grub/stage1

setup (hd0)

This command will install grub on the MBR of the first drive.

# Type quit and reboot. Everything should proceed normally.

In our case, the details were all identical except that we used (hd0,0) in place of (hd0,1) because our /boot was on the first partition of the first drive.