dual boot with dual hardisks

hi i have installed Suse 10.3 in one hardisk
and Redhat 7.3 Ent in another hardisk
i want to make dual boot of these two hardisks and
the bootloader should be suse

If both systems are able to boot as they are, you should just edit your suse menu.lst, pasting the required stanzas from your red hat menu.lst - or, even better, just entering a rootnoverify/chainloader stanza. Then all you have to do is check that the drive references are OK and off you go. By the way, to edit menu.lst, you have to be root; they’re located in /boot/grub of each system.