MS PowerToys for XP (including ImageResizer) (XP Only – No Vista)                http://www.microsoft.com/windowsxp/Downloads/powertoys/Xppowertoys.mspx

For Vista, his one http://www.codeplex.com/PhotoToysClone is supposed to be an excact duplicate of the one for XP.

Here are links to alternate software too:  http://www.vso-software.fr/products/image_resizer/ and http://www.powerhourgame.com/windows_vista_image_resizer_powertoy_prish_image_resizer.htm