Boot into any live cd which supports your hardware and the filesystem used by Suse (preferably, use a rescue disk if you can).
Mount your linux partitions under a certain directory, say /mnt/linux (Note that if you have a different partition for /boot, you will need to mount it under /mnt/linux/boot). Now chroot to /mnt/linux (
chroot /mnt/linux) and run
grub-install /dev/hda to install GRUB to your MBR.
If you used a suse rescue disk, it would probably mount your linux partitions automatically at a certain locations, probably somewhere and /mnt. All you would need to do is the chroot'ing and the grub-install bit
If some partition layout had changed after GRUB was wiped out, you will need to make the necessary adjustments to the file /boot/grub/menu.lst to reflect them.