I'm assuming you have a working grub installation with Ubuntu.
When you install Suse, be careful to specify installing grub to the root partition, and not to the MBR. Ubuntu has already done that.
When installation of the first cd is complete, and before trying to reboot to finish installing Suse, open /boot/grub/menu.lst in vim or some other text editor (have to be root to gain access to menu.lst). Copy the grub menu entry(s) for Suse, then close the file.
Mount the Ubuntu partition, and open Ubuntus copy of /boot/grub/menu.lst, and paste in the entries for Suse. Close the file.
Now Ubuntus menu.lst has info for both Ubuntu and Suse. You should be able to reboot and see both in the grub menu, and you should be able to boot into either one.
If you screw up and install Suses grub to the MBR, just reverse the instructions above and copy Ubuntus menu.lst entries into Suses menu.lst. It works either way.
Last edited by bigrigdriver; 08-02-2007 at 12:18 PM.