$urlsuch[]="/([^]_a-z0-9-=\"'\/])((https?|ftp):\/\/|www\.)([^ \r\n\(\)\^\$!`\"'\|\[\]\{\}<>]*)/si";
$urlsuch[]="/^((https?|ftp):\/\/|www\.)([^ \r\n\(\)\^\$!`\"'\|\[\]\{\}<>]*)/si";

$urlreplace[]="\\1\\2\\4";
$urlreplace[]="\\1\\3";

$text = preg_replace($urlsuch, $urlreplace, $text);

$text = preg_replace("/\[URL\]www.(.*?)\[\/URL\]/si", "<a target=\"_blank\" href=\"http://www.\\1\">www.\\1</a>", $text);

$text = preg_replace("/\[URL\](.*?)\[\/URL\]/si", "<a target=\"_blank\" href=\"\\1\">\\1</a>", $text);