<script type="text/javascript">
var lastType = "";
function changeAction(type) {
     if (document.formular.Uni.value == '') {
         alert('{log_univ}');
     } else {
         if(type == "login" && lastType == "") {
             var url = "http://" + document.formular.Uni.value + "";
             document.formular.action = url;
         } else {
             var url = "http://" + document.formular.Uni.value + "/reg.php";
             document.formular.action = url;
             document.formular.submit();
         }
     }
}
</script>

                        <center>Сервер:</center>
                        <center> <form name="formular" action="" method="post" onsubmit="changeAction('login');">
                          <div align="center">
                            <select name="Uni">
                    <option value="galaxywars.org.ru/s1/index.php">Сервер 1</option>
                    <option value="galaxywars.org.ru/s2/index.php">Сервер 2</option>
                    </select>
                          </div>
                          <p>
                          <center>
                            Ник:
                          </center>
                          <center>
                            <input name="username" value="" type="text" style="width: 150px; top: 0px;">
                          </center>
                        </p>
                        <p>
                         <center>Пароль:</center>
                         <center><input name="password" value="" type="password" style="width: 150px; top: 0px;"></center>
                          </p>
                             <p>
                         <center>
                           <span style="padding-right: 4px;">
                           <input name="submit" value="Войти" type="submit">
                           </span>
                         </center>
                             </p>
                         </form>