If you cant find the ArcExplorer software on the Atlas web site or CD go to this web address: http://www.esri.com/company/free.htm On the left hand side under software click on ArcExplorer. When the next page comes up in the center of the page is a small map with several buttons. Click on the download button. When the page finishes loading click on "Download ArcExplorer 1.X". The next page has a few versions of ArcExplorer. We want to download the latest one, currently ArcExplorer 1.1, version 2 will be out soon. Click on the corresponding text. At this point you may need to register with ESRI. It doesnt cost anything and it wont ask for any financial information. After you are finished you will end up at the final download screen. Click one of the two links in the middle of the screen. It should say "Http Redlands" or "Ftp Redlands." It should ask you where you would like to save the file. Place it somewhere on the local hard drive. (You may want to write down the location.) It should start copying the file to your local computer. Wait until it is completely downloaded then continue to step two.
When the file has finished downloading go to the file location using windows explorer. (Dont get windows explorer mixed up with internet explorer) Double click on the file name. Currently, its called aeclient.exe. After double clicking on the file it will uncompress itself and start the installation. Follow the onscreen directions. When it is finished loading you can double click on the icon on the desktop or under the start/programs menu to start the program.
Visit Digital Tutorials for resources on using ArcExplorer and GIS technology.