DapperDan, your as bad as me with the kernel entries!
 
I don't have my Fedora box open right now for reference, but you can add Fedora Core 2 to the grub file.
 
Since you are using Kernel 2.6 you can forget the ide-scsi driver, which should not be needed.
 
1. Mount the Fedora Core 2 partition.
 
2.Copy the vmlinuz and initrd to your boot directory of the original Fedora install that has grub installed on it. I like to make a directory in the boot drive for other versions and distros. In your case, the boot is hda1. If you elect to just put the files in the boot directory directly, then you don't have to point to the Fedora Core 2 directory.
 
So, cp the files to the boot directory.
 
3. Add/copy one of the old fedora entries in the grub menu file as the second to last entry, or wherever you wish, then edit it. The syntax should like like;
 
title Fedora Core_2
root (hd0,5)
kernel /vmlinuz-(version of kernel) ro root=LABEL=/ (omit ide-scsi)
initrd /initrd-(version of initrd)
 
I believe that in Grub, the partitons begin with "0" so, the partition 6 on hda1 should be (hd0,5). If you get a kernel panic error on boot, try changing it to (hd0,6).
 
I think that you should be able to edit Grub at the boot menu, when it first comes up, if memory serves me right. So, if all the entries are right (except the partition) then you can edit the entry at the boot menu. When the menu comes up at boot, highlight the entry you want to edit, hit "e" and see if it brings you into edit mode, if you need to edit the entries. Esc backs you out of edit mode, "b" tells it to boot the edited entry, in your case Fedora Core 2.
 
 

Just as a warning I don't use Fedora. This is just a semi-educated guess as a Gentoo user.
 
First check /boot and make sure that you have an initrd adn vmlinuz for kernel 2.6.5, this is what the Fedora site said the kernel was.
 
Fedora seems to use the mountpoint for root(in the third line), I put the device path my example (root=/dev/hda6). Check /etc/mtab or /etc/fstab to get the mountpoint, you can also try just keeping /dev/hda6, if it doesn't work it shouldn't effect the anything but the core 2 entry.
 
Add this to the very bottom.
 
title Fedora Core 2 (2.6.5-(1.358).nptl)
root (hd0,0)
kernel /vmlinuz-2.2.6.5-(1.358).nptl ro root=/dev/hda6 hdc=ide-scsi hdd=ide-scsi
initrd /initrd-2.6.5-(1.zzzz1.358).nptl.img
 
Also check this http://www.fedoraforum.org/forum/showthread.php?s=&threadid=2763.

Thanks guys! I tried something a little different. I copied my entire original /boot to my home directory, then reinstalled Core 2 and let it overwrite my /boot partition. After booting to Core 2, I essentially copied everything from my old /boot and /boot/grub/ that WASN'T in the new /boot and transferred it over. The other kernels listed above, were not needed, but were just for experimenting but I did need, kernel 2.4.22-1.2115.nptl for Win4lin. I edited /boot/grub/grub.conf thusly..
 

Code:

# grub.conf generated by anaconda# added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstalldefault 4# end added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstall# 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 (hd0,0)#          kernel /vmlinuz-version ro root=/dev/hda6#          initrd /initrd-version.img#boot=/dev/hdadefault=1timeout=10splashimage=(hd0,0)/grub/splash.xpm.gztitle Fedora Core 2 (2.6.5-1.358)       root (hd0,0)    kernel /vmlinuz-2.6.5-1.358 ro root=LABEL=/1 rhgb quiet initrd /initrd-2.6.5-1.358.imgtitle Fedora Core 1 (2.4.22-1.2115.nptl)  root (hd0,0)    kernel /vmlinuz-2.4.22-1.2115.nptl ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi    initrd /initrd-2.4.22-1.2115.nptl.img# added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstalltitle Win4Lin      root (hd0,0)    kernel /win4lin ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi       initrd /initrd-2.4.22-1.2115.nptl.img# end added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstall

 
I don't know if I did it by the book, but everything is working perfectly, and I can now boot between Core 1 and Core 2 with ease from the grub menu!
 
Thanks again!