If you have 49,587 image files spread across your computer (spookily, the same number that I have) then wouldn't it be nice to find a FREE program that finds any duplicates for you?
If you're not a complete GIBBON with a computer then try out VISIPICS.(http://download.cnet.com/VisiPics/3000-2193_4-10424234.html).
This one will take you a few minutes of concentration to get the hang of it, but what's the alternative, and hour of shuffling windows and files? Two hours?