function init_menu_rollovers() {
    var nav = document.getElementById('nav');
    var imgs = nav.getElementsByTagName('img');
    for (i = 0; i < imgs.length; i++) {
        if (imgs[i].src.indexOf('active') >= 0) continue;
        imgs[i].onmouseover = function() {
            this.src = this.src.replace(/\.png/,'_hover.png');
        }
        imgs[i].onmouseout = function() {
            this.src = this.src.replace(/_hover/,'');
        }
    }
}

DKI.addEventSimple(window,'load',init_menu_rollovers);