Do you have the original Windows XP cd? Or the windows cd that came with the manufacture PC? So long as you have that and the CD-KEY you can run a repair on the Windows XP system and this will fix it. Once you boot off the XP CD the first screen will appear just hit ESC then F8 to accept the agreement.. (if I recall these steps in the right order) then it will say "looking for previous versions of windows" it will find your old one located at C:\WINDOWS then it will ask you if you want to repair you push "R" and the repair process will begin.
If you are getting stuck through the installation then it could be the CD is dirty, the CD-ROM drive is dirty. I would clean the CD-ROM drive and if that doesnt work isntall another CD-ROM drive and see if that works.