Find (and eliminate) duplicate files, folders, and photos?

Is there any tool that can help me find duplicate files and folders on my hard-disk? Preferably a simple freeware tool?

I have a 18GB photo dump created by my friend that I am sure has a lot of repeated albums with various folder names. Looking for an easy way to cut down this bulk to unique photos before manually sorting / organizing them.

Is there any tool that specifically helps us organize photos that are scattered across a drive? (all digicam photos – so EXIF info should be present)

Optional: Does any tool find duplicate files irrespective of the file names being same of different :) ?