function OpenRegisterNewsletter() {

    var winSettings = "center:yes; status:no; resizable:no; dialogHeight:180px; dialogWidth:380px;";

    var args = window.showModalDialog("/Pages/RegisterNewsletter.aspx", null, winSettings);
}

function OpenRegisterWebinar() {

    var winSettings = "center:yes; status:no; resizable:no; dialogHeight:295px; dialogWidth:420px;";

    var args = window.showModalDialog("/Pages/RegisterWebinar.aspx", null, winSettings);
}