I am using OpenSuse 11.3 32bit with no GUI running off /dev/sdb and /dev/sdc. My current menu.lst works fine. When I try to add a section for the old distro, grub appears to get confused by the (hd0,0) configuration and does not find the correct file system (ext2). When I change it to (hd2,0) it finds the file system but reports “file not found”. I assume this is because there is no initrd. I changed the partition references to sd instead of hd for compatability.
Unfortunately if you used to boot that disk by changing the drive order in the BIOS, the lines will not work when another drive order is active. You will have to change (hd0,0) everywhere to (hd2,0) and also change hda to sdc. You can experiment without modifying menu.lst (in 11.3) by using the interactive mode of grub. Just type in: