it can be done with some quick-n-ugly batch file.
May require you to use a text editor with column copy-n-paste though.
in your screenshot folder, do a "dir /b >screens.bat"
then edit screens.bat, replace ".png" (or whatever your screenshots are) with ".zip .." (or whatever file you want to delete)
then just insert at the beginning of each line "move " (that's the tough part, where a column based editor will help)
That will move all the zipfiles that match your screenshots up 1 folder. Delete anything leftover, and move the .zip files back into the directory they used to be in.
Not pretty at all, but it should do the trick.
-jeff!