Deleting Windows Xp User

[ted37]

Recently I deleted an accound of a user in my PC. By mistake I didn't create a backup directory of the documents this user has created.
When I run "RECOVER MY FILES", I got a lot of recoverable files (between them some very old ones), but only a few that belonged to the deleted user.
Is it a normal limitation of the program, or WIN XP completely destroy the data of a deleted user for privacy reasons?
P.S. Anyway don't bother much cause there is a possibility that someone from my office has used my PC, overwriting the deleted files, so that they appear to be unrecoverable.