A repair installation using the Dell disk. Press F2 to get to the BIOS and change the sequence of booting to CD Rom. Put the Dell disc in your cd Rom drive and start to install. When the option for repair (not the first one which is through the Recovery Console) choose it. You will get a new My documents folder, and a new sign in signature, but your data should remain. For more information visit either of these sites :
http://www.michaelstevenstech.com/cleanxpinstall.html
http://www.winsupersite.com/showcase/windowsxp_sg_clean.asp