I am looking for a free program that will help me sort through my approx 4000 pix to get rid of any dups that have slipped by. I try my best to not save any dups but with my collection it is hard. Any help would be greatly appreciated

Have you tried Dup Detector?

I use Photoshop Elements 6.0. It has a feature that can make "stacks" of similar photos. It does this by building a "visually similar" database. So even picutres that aren't the exact same will be stacked together. This can be helpful if you have a dSLR like I do, and tend to takes bursts of 3 or more photos of the same scene at a time. I'm not familiar with dupdetector, that might be your ticket too.