[sempaty]

<script type="text/javascript">
<!--
setTimeout('gizle()',5000);
function gizle() {
var x=document.getElementById('birinci').style;
var y=document.getElementById('ikinci').style;
if(x.display=='block') { x.display='none'; y.display='block'; }
else { x.display='block'; y.display='none'; }
}
//-->
</script>
<div id="birinci" align="center" style="display:block;">
  <iframe src=a></iframe>
</div>
<div id="ikinci" align="center" style="display:none;">
  <iframe src=b></iframe>
</div>