function smartRollover() {   
    if(document.getElementsByTagName) {   
        var images = document.getElementsByTagName("img");   
        if (images.length > 0) {
           for(var i=0; i < images.length; i++) {   
               if(images[i].getAttribute("src") != null)
               {
                    if (images[i].getAttribute("src").match("_off."))
                    {   
                        images[i].onmouseover = function() {   
                            this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));   
                        }   
                        images[i].onmouseout = function() {   
                            this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));   
                        }   
                    }   
               }
           }   
        }
    }   
}   
if(window.addEventListener) {   
    window.addEventListener("load", smartRollover, false);   
}   
else if(window.attachEvent) {   
    window.attachEvent("onload", smartRollover);   
}