triple boot with linux

I have Windoze xp and Opensuse as a dual boot system right now. All i want to do is put another linux distro (say fedora core) and triple boot my system.
now i tried many ways and i always end up having the latest installed linux and losing the one installed before it. i tried fiddling with grub but i am still a noob and i am not able to get the two linux distros on my grub.
even if i try to give them a valid path...it says that partition is not mounted during boot and hence it cannot access the boot images and initrd.
please help me as i have been stuck with this problem for a long time....
as always any help is sincerely appreciated!!!
thanks n c ya!!