I'm assuming you have xp on the first (master) drive, and Fedora on the second (slave) drive.
What probably happened is that you wrote grub stage 1 to the MBR of the slave drive, when it should be on the MBR of the master drive.
You should be able to boot Fedora from the install cd. Then follow instructions in the grub manual to write grub stage 1 to the MBR of the master drive. If it's hda, you would specify 'root (hd0)' (the boot sector of the drive. Be careful and do not add the partition number, or you will overwrite part of the xp partition and you will have to re-install xp to fix it).
After that, it's something like 'grub-install (hd0)' (I don't remember exactly. I usually just look up the manual and read it again when tweaking things).
Other than that, it would be helpful if you posted your grub.conf and possibly /etc/fstab (the part naming disk partitiions [devices] and their mount points).