Here is a new Web site that will resize your images online for free. They can also optionally put a text watermark on it to deter downloaders from using it as their own.
The site is run by the same company that provides the software that runs Oldgas.com Shop Talk. I'm hoping that the next upgrade to their forum software will have the resize feature built in.
Give it a try:
http://cranno.com/After you get to cranno.com ...
Select your image by clicking "Browse"
Leave the resize choice at 640 x 480
Click "Convert"
Then after it works, click "Download"
The image file you download from Cranno will be the image you select for File Manager on Oldgas.com Shop Talk
Pictures of the step-by-step File Manager image upload process:
http://www.oldgas.com/forum/ubbthreads.php?ubb=showflat&Number=129148#Post189696