function smartRollover() {  
        if(document.getElementsByTagName) {  
            var images = document.getElementsByTagName("img");  
            for(var i=0; i < images.length; i++) {  
                if(images[i].getAttribute("src").match("."))  
                {  
                    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);  
    }