Maybe you don't have it set up when it boots up to check for the CD first? Go into bios by pressing Del usually *no pun intended* at bootup (it will say otherwise somewhere at the bottom or right)
Go into the first menu and check that it is set that the cd rom drive is read before the hard drive is
First Boot device: CD Rom
Second Boot Device: IDE-01 *doesnt always have to be IDE-01 (which is the Hard drive)
So just change these to make the order so that it will see the cd first before it attempts to boot Fedora.
Then Save and Exit.
EDIT: If you have a flopy drive you could use too before sending it off, maybe set the second boot device to : Floppy, and the third boot device to the hard drive. Thats if it has 3 options.
Now put the disc in again and restart. Hopefully it'll see it first and start booting from it.
Windows setup will then format the drive before placing XP on it
Hope this helps
You've also taught me something new. I didn't know there was an operating system called Fedora Core. Sounds good though with the 3rd party app's it contains... and is free?