If you run XP the absolute best (easiest and simple) way it to download the MS Power Toys and download the image sizer. Its as simple as a right click the photo and pick the size you want and it will make a copy of your original (leaving it alone) and making you a copy. It will do 1 picture or 100!!! They also have a RAW viewer. No doubt about it!
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
