Renaming multiple files at the same time

A folder contains about 100 images from my camera.  They are named in succession IMG 001 - IMG 098.  I want to move them to another folder but most of the names are in use in the To folder. So I need to change the names and I don't want to do it one at a time. All I need to do is put something at the beginning {at the end would change the extension} say a ^.  Can I do this? If so, how?

Appreciate any help.