I have been using the Gif resizer Tool on this website:
It works on JPEGS (normal picture type). It is a little clunky. When I have to make a second attempt at resizing a picture I have to clear all the size boxes or it does the same thing again.
If I just used one camera (or one size of file) I could just keep entering the same % to get the smaller (under 200 MB) file for the Thumbnails. I just drag and drop the pic from my download folder to the drag and drop box.