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."));
                }
            }
        }
    }
}

/*20071109 IE6スクリプトエラーのため
function highlightpage(){
    if(!document.getElementsByTagName) return fales;
    if(!document.getElementById) return fales;
    if(!document.getElementById("menu")) return fales;
    var nav = document.getElementById("menu");
    var links = nav.getElementsByTagName("a");
    for(var i=0; i<links.length; i++){
        var linkurl = links[i].getAttribute("href");
        var currenturl = window.location.href;
        if(currenturl.indexOf(linkurl) != -1){
            var linkimages = links[i].getElementsByTagName("img")[0];
            var src_replace = linkimages.getAttribute("src").replace("_off.", "_on.");
            linkimages.setAttribute("src",src_replace);
        }
    }
}


**ここは未動作で**

if (document.all) {
    var src_replace = linkimages.getAttribute("src").replace("_off.", "_set.");
    alert("IEとか");
}else if (document.getElementById) {
    var src_replace = linkimages.getAttribute("src").replace("_off.", "_set.");
    alert("FF");
}
*/



if(window.addEventListener) {
    window.addEventListener("load", smartRollover, false);
    /*window.addEventListener("load", highlightpage, false);*/
}
else if(window.attachEvent) {
    window.attachEvent("onload", smartRollover);
    /*window.attachEvent("onload", highlightpage);*/
}