Well, I have a little problem. I have been rather sloppy

at backing up my files in an external 80GB drive, and I just usually just drop all the contents from "My Documents" in there, as well as some other junk.
Well, I have backed up enough junk that I am running out of room
So, my question is, is there a software out there, that would search for all duplicate files, list them, show you the size and last modified date, and allow you to delete the duplicate ones?
Anyone heard of such a utility that you recommend?
Thanks