[dscoma]

Определить версию IE можно и так:

JS

<script type="text/javascript">
//<![CDATA[
if (navigator.userAgent.indexOf(IE 6) != -1)
        document.write(<style type="text/css" media="all">@import url('ie6.css');
//]]>
</script>

SSI

<!--#if expr="$HTTP_USER_AGENT=/Windows/" -->
<!--#set var="ua" value="Explorer" -->

PHP

<?php
if (strpos($HTTP_USER_AGENT,"Windows") !==false) {
     $ua="Explorer";
     $uaVers = substr($HTTP_USER_AGENT,strpos($HTTP_USER_AGENT,"MSIE")+6);
     }
else {
     $ua=$HTTP_USER_AGENT;
     $uaVers=""; 
     }
?>