Serializing WITHOUT xmlns

No problem - just pass an empty string as the default namespace to the XML serializer:

XmlSerializer newSerializer = 
   new XmlSerializer(typeOfT, "");

Unfortunately, there's no easy constructor overload if you really need to define the XmlAttributeOverrides and the default namespace - so either you can skip the XmlAttributeOverrides and use that constructor I mentioned, or you need to use the one that defines all possible parameters (including XmlAttributeOverrides and default XML namespaces - and a few more).

A working solution, for the record!

var ns = new XmlSerializerNamespaces();
ns.Add("", ""); 
var serializer = new XmlSerializer(yourType); 
serializer.Serialize(xmlTextWriter, someObject, ns);