Occasionally, I used the file utilities section of an old registry cleaner (jv16) that used to be freeware (but isn't anymore) for this purpose. But with a backup copy of my whole Windows folder and two copies of my Internet site on my hard disk it isn't practical anymore. I certainly can imagine circumstances where it is practical, but not for me at the moment.
Anyway, http://www.google.com/search?&q=%22duplicate+files%22+freeware seems to find quite a number of programs that you can try. But I can't recommend any from my own experience.
I am looking for a program which searches for duplicate files. I tried 'Dupeless' which is very thorough and not shareware, but it is not always specific to the root of the files it finds, which means that removing the duplicates can, (and has) caused me to delete files needed. I am more concerned with items listed in Word, Notepad, etc. rather than 'left border.gif' files, etc. Perhaps it might be part of a general file manager program.