i have formatted my windows xp and the grub is lost too.i think is not erased but i can't access it because the MBR is different now.i have the rescue disk but i don't know what to do with it..
my installation is fedora core 2.the grub is installed in a different partition of the same disc(standard installation)
thanx...

Boot using the Rescue CD (or the installation CD-1 and enter “linux rescue”), allow it to search for the fedora installation and when it stops at a command prompt, type the commands “chroot /mnt/sysimage” followed by “grub-install /dev/hda”, assuming your hard drive is /dev/hda. Grub-install is described in the Grub manual (www.gnu.org/software/grub/manual/grub.html) section on “Installing GRUB using grub-install”.

If that fails, read the Grub manual section on “Installing GRUB natively” and enter the command “grub” followed by the commands “find ...”, “root ...”, “setup ...” and “quit” at the grub> prompt as is describe in the manual.

If that fails, read the Grub manual section on “Creating a GRUB boot floppy” or “Making a GRUB bootable CD-ROM” and make a Grub Boot Floppy or CD from the command prompt. The floppy is easier to make, but is not very useful on laptops. Boot using that floppy/CD to the grub> prompt and use the “find ...”, “root ...” and “setup ...” commands as described above. A Grub boot floppy/CD is a nice thing to have around.