Its recommended to take a backup if the data is precious before doing these kind of adventure.
DON'T WORRY :-)
First i would like know whether the Fedora can boot sucessfully or not ?
if its not booting then, please post the Error message or explain me what will happen during the time of booting.
If its booting sucessfully then it's possible to boot the XP from both C and D drive from the GRUB, when you select the window XP OS from the GRUB then it passes to windows bootloader there you can see both the xp of C and D