''Depending on your version of Windows and the recovery system you use, some of your settings and files may be saved when you restore your computer to factory settings. However, it is best not to rely on this so back up any files you wish to keep beforehand''
If you Hard Drive has the space, partition it and copy over the files you need to keep, then just reinstall XP on the original partition leaving the new partition intact
You CANNOT re-partition reliably the partition you are working on and just copy stuff over. There are one or two software apps you 'can' try .. but I wouldn't advise it.
Liken it to pulling the rug out from under your feet and hoping you don't fall over.
BACKUP everything first!