Image Resizer

Microsoft's PowerToys for Windows XP has an Image Resizer. to resize you right-click the image and select "resize pictures" then on the next screen you pick the size you want.
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
direct download

 

Thanks iceni for the link

 

I haven't tried that one (yet), and this is slightly off-topic but closely related, so bear with me ...

If you're using IE-6 and have the auto-resize feature turned on (handy for on-line viewing), and you want to "Save Picture As ...", set the image back to full size first. Nearly any graphics program around can resize the saved image to whatever you want with far less loss of quality than IE does.