I use the power toy image resizer that is free from Microsoft- YES!!! Something free from microsoft. Go down to where you see image resizer on the right and click the link and download.

http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx

Another free tool I like very well to resize images with is Picasa. It is also a great program to organize all of your pictures on your computer.

http://picasa.google.com/download/