How to convert from XmlTextWriter to String?

public string CreateXML(string strAuth,string strTran,string strDL,string strCode,string strMsgCode,string strMessage)
{
string xmlString;
StringWriter sw = new StringWriter();
XmlTextWriter writer = new XmlTextWriter(sw);
// start writing!
writer.WriteStartDocument();
writer.WriteStartElement("Result");
writer.WriteElementString("Authentication", strAuth); writer.WriteElementString("Transaction", strTran);
writer.WriteElementString("DL", strDL);
writer.WriteElementString("Code", strCode);
writer.WriteElementString("MsgCode", strMsgCode);
writer.WriteElementString("Msg", strMessage);
writer.WriteEndElement();
//Write XML, and then flush the writer...
writer.Flush();
//Return text from string writer...
xmlString = sw.ToString();
//close the Objects
writer.Close();
sw.Close();
return xmlString; }