site  http://www.obviousidea.com/windows-software/light-image-resizer/

another download site http://www.softpedia.com/get/Multimedia/Graphic/Graphic-Editors/VSO-Image-Resizer.shtml

favorite download site http://download.cnet.com/Light-Image-Resizer/3000-2193_4-10529104.html

I used to have VSO version 3. something.  This company evidently bought the program.  When I downloaded it, it was free but it nags.  However they had a deal, if you friended them on Facebook you get a code and then it's just like you bought it.  I've had it for over a week and no spam etc. so I'm not worried.  If you don't mind the little nag then don't friend it.  The nag isn't bad, just a popup screen saying continue-register-buy or something like that.

What makes it great for this site is it will convert any picture into a 100 kb size.  No guess work.  It has a setting for just that size.  It will also let you pick any size 640x480 or 1024x768 etc.  It will convert to another type, jpeg to tiff etc.  It will post to facebook, it will email.  It does a lot of other stuff.

Lastly it hooks into you right click popup menu in Windows.  So you can right click on a picture in a folder and choose what you want to do with it.

On that menu it's listed as Light Image Resizer.

Has a tutorial too.