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