These are windows .ico files to be used in creating desktop shortcuts to the Sirius online player application. Create a new shortcut to http://www.sirius.com/servlet/MediaPlayer? and give it a name. Right click, choose properties, and then hit the Change Icon button. Browse to the location you saved the .ico of your choice to. Finally, hit OK. Now click it, log in and rock out.
Mouse over, save as, preserve the .ico extension using these images