Abrir un opoup desde un formulario

[php.java.jsp]

Código:

<script type="text/javascript">

function enviar(){
	ventana = window.open("","ventana","width=660px,height=500px");
	document.form1.target = "ventana";
	return true;
}

</script>



<form name="form1" action="popup.php" method="post" onsubmit="return enviar()">
<input name="nombre" type="text" id="nombre">
<input type="submit" name="Submit" value="Enviar">
</form>