I USED FEDORA CORE 11 64 BIT...
1) boot using Fedora DVD
2) at boot prompt, enter linux rescue. this takes you to linux rescue mode
3) run the command chroot /mnt/sysimage
4) now, run grub-install /dev/???? (eg: grub-install /dev/sda0 to install grub to first partition on sata 0 HDD)
sometimes, when you run linux rescue at boot prompt, it takes care of everything.
one reference:
*www.linuxquestions.org/questions/general-10/how-to-restore-grub-after-win-xp-install-446952/