get_browser_ (See related posts)

function get_browser_($user_agent)
{
	$browsers = array(
		'Opera' => 'Opera',
		'Mozilla Firefox'=> '(Firebird)|(Firefox)',
		'Galeon' => 'Galeon',
		'Mozilla'=>'Gecko',
		'MyIE'=>'MyIE',
		'Lynx' => 'Lynx',
		'Netscape' => '(Mozilla/4\.75)|(Netscape6)|(Mozilla/4\.08)|(Mozilla/4\.5)|(Mozilla/4\.6)|(Mozilla/4\.79)',
		'Konqueror'=>'Konqueror',
		'SearchBot' => '(nuhk)|(Googlebot)|(Yammybot)|(Openbot)|(Slurp/cat)|(msnbot)|(ia_archiver)',
		'Internet Explorer 6' => '(MSIE 6\.[0-9]+)',
		'Internet Explorer 5' => '(MSIE 5\.[0-9]+)',
		'Internet Explorer 4' => '(MSIE 4\.[0-9]+)',
	);

	foreach($browsers as $browser=>$pattern)
	{
		if (eregi($pattern, $user_agent))
			return $browser;
	}
	return 'Unknown';
}

echo get_browser_($_SERVER['HTTP_USER_AGENT']);