Boot into the live Ubuntu cd. This can be the live installer cd or the older live session Ubuntu cds.
When you get to the desktop open a terminal and enter.
Code:
sudo grub
Code:
find /boot/grub/stage1
Next, THIS IS IMPORTANT, whatever was returned for the find command use it in the next line (you are still at grub>. when you enter the next 3 commands)
Code:
root (hd?,?)
Next enter the command to install grub to the mbr
Code:
setup (hd0)
Code:
quit
When you reboot, you will have the grub menu at startup.