I have bought a SoftWare called DeDupe for deleting the duplicate files,it increases the hard disk space and can also compress duplicate files in to a zip file.
Iam finding this Software very useful compared to all the other products that are offered for the same use.
If you are really looking for a SoftWare having the above Qualities log on to
www.cellarstone.com/dedupe.htm
Go get it
Good Luck
LEE Cooper