function load_menu_images(){    
    // load button hover images
    load_images( new Array("/images/buttons/grey/left_hover.gif",
                           "/images/buttons/grey/right_hover.gif"));

    // load ajax cart images
    load_images( new Array("/images/buttons/add_btn.png",
                           "/images/buttons/addroll_btn.png",
                           "/images/buttons/remove_btn.png",
                           "/images/buttons/removeroll_btn.png",
                           "/images/buttons/addall_btn.png",
                           "/images/buttons/addallroll_btn.png",
                           "/images/buttons/removeall_btn.png",
                           "/images/buttons/removeroll_btn.png",
                           "/images/ajax/ajax-loader-23-grey.gif",
                           "/images/ajax/ajax-loader-23-w.gif"));
}

function load_images( array_of_paths ){
    for( var i=0; i<array_of_paths.length; i++)
        load_image( array_of_paths[i] );
}

function load_image( path ){
    img = new Image();
    img.src = path;
}

// call the load images function when after the window has loaded.
Event.observe(window, 'load', load_menu_images, false);