Before I ask my question, here is my setup:
1. I installed XP pro and I backed it up.
2. I installed Suse 10.2 with GRUB active i.e. when I boot, GRUB loads and I can select which OS I want.
2. My partition on which I had XP got corrupted and I had to re-format and reload from the backup.
3. when I reloaded from the backup, the MBR was the original one, without GRUB. So, now when I boot, it goes directly into XP. I don't see Linux anymore.