restoring grub after windows xp

sorry, it's a so common question, but googling gave me several ideas and I am embarrassed: Could someone give a direct hint about the best way to restoring grub as my boot loader? It already has suse 9.3, slackware 9.3, slackware 10.1, windows 98 - and as we know windows xp (x64) overwrites the grub. I need to restore GRUB in order to boot SuSE 9.3 and add Windows XP in its menu thru YaST. Thaks for any help a.