I dont think your problem lies with Fedora. Is the XP install disk from Dell a MS Windows install disk or a Dell system / software recovery disk. There is no reason I can think of that would stop XP installing on a working system but OEM compiled recovery disks often have anti piracy protection and they look for a key on your system. If this is the case you'll have to talk to Dell.
One other note, when you do reinstall XP it will overwrite your Fedora install. Linux distros recognise other operating systems but Windows is not so polite.
Stop making excuses, start making progress.