I have resized photos for a couple of people, and whilst I don't mind doing it ocassionally, I have recently changed internet providers and only have a finite download limit before I get my speed reduced.
Here are a few free programs you can use to edit your own photos
Picasa 3: Free download from Google
Photoscape : Free Photo Editing Software (Photo Editor) Download
this last one is the most simple and should work for everyone
Resize Photos - Free Online Photo and Image Resizing - Resize Digital Photos
You really want a photo that is 500-600 X 600-700 pixels ideally.