If you want to refresh WinXP
Boot from the CD and skip the first screen of the console repair as though you want a new install.
To new install will detect the current installation and would offer repair (Prees R_.
If you choose Repair it actually reinstall the whole OS on the same partition without touching the Applications, and Data (takes 30 min or more depending on the computer's hardware).
That is different from Vista and Win 7 that actually are trying to Repair the current OS installation.