The ArcMap 3D Viewer is available for usage only when the ArcGis is installed correctly. Go to Start > All Programs > ArcGIS 8.3 Demos > Documentation (Word). Make sure you have a compatible Office package installed then click that link to file. Use the information you find in the file to properly install the viewer and launch the MXD file which acts as a demo script. You also have to enable the toolbar in the application.