var picname;

    function hi(picname)
    {
    Highlight = new Image();
    Highlight.src = "pics/nav_" + picname +"_p.gif";
     window.document.images[picname].src = Highlight.src;
    }

    function lo(picname)
    {
    Normal = new Image();
    Normal.src = "pics/nav_" + picname +"_g.gif";
     window.document.images[picname].src = Normal.src;
    }