If you need to run a simple resize of a whole batch of JPG files then Picture Resizer is probably the easiest way to do it. Just rename the program's 389KB executable to indicate the size you need on the longest axis - PhotoResize640.exe if you're resizing from 800x600 to 640x480, say - then drag and drop the images onto the program and it'll resize them for you, storing the new versions in the same folder (Picture.jpg would become Picture-640.jpg).
You want to resize by a percentage, or without preserving the aspect ratio? Picture Resizer can do that, and more - the author's site explains all.
[http://www.rw-designer.com/picture-resize]
