Using the utility couldn't be simpler—just right-click one or more pictures, select Resize Pictures, choose the resolution you want to resize the images to, and the newly resized images will show up alongside the originals—making this a very handy tool for quickly resizing images to share over email or instant message.
If this sounds familiar, it's because the utility is a clone of the previously mentioned Image Resizer Powertoy—but that one only worked on Windows XP, and only for 32-bit, but this one is both Vista and 64-bit friendly for your image resizing tasks.
The Image Resizer tool is both free and open source, available for Windows only. For more, check out the previously mentioned Bulk Image Resizer, or take a look at the top five image editing tools. Thanks, syndprod!