Its easy depending on what operating system you are using. XP has a very simple way to do it using the "Image Resizer" powertoy (http://www.microsoft.com/windowsxp/pro/downloads/powertoys.asp). Download and install it and then right-click on the image from the explorer or my computer.

Otherwise you will need some type of image manipulation software. Most scanners come with something like ArcSoft, Adobe Photopublisher LE, or something that has this capability. Should be pretty straight-forward through the menu. Check out the help file that came with the software.

Another option is a small freeware program like Mihov image resizer (http://downloads-zdnet.com.com/3000-2192-10143186.html?tag=lst-0-1) which is designed just for rotating and resizing images. Very easy to use.