Hmm that is actually different than the one I have been using: http://isse.cr.usgs.gov/arcgis/services/Combined/SDDS_Imagery/MapServer/WMSServer?SERVICE=WMS&VERSION=1.1.1&STYLES=&SRS=EPSG:4326&FORMAT=image/png&layers=0&request=map& Wonder if they both go to the same imagery set or not...