Microsoft windows XP users can use also use an XP PowerToy free from Microsoft to resize their images.  This PowerToy enables you to resize one or many image files with a right-click.  Simply download and install the ImageResizer PowerToy from the link below.  Then, right-click on any picture you wish to resize and choose 'Resize' 

ImageResizer.exe
521 KB 28.8 Kbps

If you don't have Microsoft Windows XP you can easily resize your photos on the web using a website such as Resize2Mail.
Resize 2 mail is an online resize website utility developed for digital camera owners, webmasters, people travelling or anybody who quickly wants to resize a digital image for email or publishing on a web site. 

http://www.resize2mail.com/