Photo Magician is a free and lightweight (less than 1MB) program for Windows that allows you to batch convert a directory of photographs. It’s similar in functionality to Photoshop’s “Image Processor” feature, with one difference being you can’t select the output quality like you can using Photoshop.
The program also features a “Quick Convert Mode”, which minimizes the program to a little box onto which you can drag and drop folders of images. If you’ve been looking for a quick way to resize images in Vista (like the Image Resize PowerToy allowed you to do in XP), then you might want to check out this program.
P.S. For a more powerful free program that’s even more similar to Photoshop’s Image Processor, you can check out BIMP Lite.