You'll need to download a live CD, such as System Rescue CD
and boot it. Now you need to make a directory to mount your Fedora partition:
Next, you need to mount your Fedora partition:
mount -t auto DEVICE /fedora
DEVICE is the device UNIX and UNIX-like kernels like Linux use to access your Fedora partition. If you remember what the /boot partition was when you partitioned your drive(s) when installing Fedora, use that. If you didn't make a /boot partition, use the / (root) partition. If your Fedora partition is on the second partition of the first IDE drive, it would be /dev/hda2. If it was on the third partition of the second drive, it would be /dev/hdb3. If you don't get this there's sure to be a little tutorial explaining it on Google or something.
Now you need to edit GRUB's configuration file (if you mounted a /boot partition, remove the '/boot' part in the filepaths below):
whatever you perfer. (I perfer nano.)
Your grub.conf should look something like:
# grub.conf generated by anaconda
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd1,0)
# kernel /boot/vmlinuz-version ro root=/dev/hda2
# initrd /boot/initrd-version.img
title Fedora Core (2.6.11-1.1369_FC4)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda2 rhgb quiet
title Windows XP
Now, comment out (put a # in front of) the line "hiddenmenu" and change "timeout=NUMBER" to something really big like "timeout=99999999999999999999999999999999999999999 9999999999". If you want to boot in text mode, remove "rhgb" from the kernel line. If you want a 1280x1024 command prompt on tty devices, add vga=794 at the end of that line. Now save and exit your editor (Esc :wq on vi, Ctrl+X on nano). Last, reboot with:
and take the live CD out of your drive. If System Rescue CD hangs at something like "Stopping USB and PCI hotplugging systems...", just manually restart your computer by pressing the power button.