Can I re-enable user's after a WinXp re-install?

I have a WinXP/Home SP1 system from a client that I have tried everything to repair. (The son downloaded KaZaa and dad hit the roof. He went into Add/Remove programs and starting deleting anything he didn't recognize, and he knows next to nothing about computers). I've cleaned virus's, adware, applied Windows Updates, the whole 9 yards but I have not been able to get around a problem accessing the CD drive.

Before doing a reformat of the hard drive and reinstall I tried to lay down WinXP on top of itself. Worked OK so far. Now I would like to recover/enable anything existing that I can. I can see the folders for users that existed before are still there but my desktop is blank.

Is there a way I can reinstate the desktops and/or the user accounts?

THanks