<input type="submit" id="login" disabled style="WIDTH: 72px; HEIGHT: 24px" >
<script language="javascript">
     var t1=8;                   
     function delay()
     { 
        if (t1 < 0)
  login.disabled=false;
else
  login.value=""+t1+"秒后提交";

        t1--;
      }                 
      window.setInterval(delay,"1000");
</script>