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."));}
      }
    }
    var input = document.getElementsByTagName("input");
    for(var i=0; i < input.length; i++) {
      if(input[i].getAttribute("type").match("image"))
      {
      if(input[i].getAttribute("src").match("_off."))
      {
        input[i].onmouseover = function() {this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));}
        input[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);}