<?
if(eregi("opera",$HTTP_USER_AGENT))
$browser = "OP";

else if(eregi("msie",$HTTP_USER_AGENT))
$browser = "IE";

else if(eregi("Mozilla.[4.]",$HTTP_USER_AGENT))
$browser = "NS";

else if(eregi("Mozilla.[5|6]",$HTTP_USER_AGENT))
$browser = "MO";

else
$browser = "FN";

if ($browser == "IE") {
echo "Интернет експлоер";
}

else if ($browser == "NS") {
echo "NetScape";
}

else if ($browser == "OP") {
echo "Opera";
}

else
echo "Хз";
?>