create xml file from flash

[aaloo]

this is my as3 code which is making an xml file

var submitListener:Object = new Object();
 submitListener.click = function() {
 var login_xml:XML = new XML("<login password=\""+username_txt.text+"\" username=\""+password_txt.text+"\">  password_txt.text  </login>");
 login_xml.xmlDecl = "<?xml version=\"1.0\" ?>";
 packet_txt.text = login_xml;
 };
 submit_btn.addEventListener("click", submitListener);

i want to insert password as node value in login node . the above syntax is not working.how it can be done?

and i also want to know how to save this xml file on hard disk?