function openPortal() {
    var str = "toolbar=0,status=0,menubar=0,scrollbars=1,resizable=0,";
    if (window.screen) {
        var aw = screen.availWidth;
        var ah = screen.availHeight;
        posH = aw / 2 - 300;
        posV = ah / 2 - 150;
        str += "width=820,height=600,screenX=" + posH + ",left=" + posH
        str += ",screenY=" + posV + ",top=" + posV
    }
    sRep = window.open("portal.aspx", '', str);
}