using System.Xml;

public class Test20031016
{
   public static void Main (string[] args)
   {
      XmlDocument doc = new XmlDocument();
      doc.Load(@"test20031011.xml");
      XmlElement element = (XmlElement)
      doc.GetElementsByTagName("PRIMOELEMENTO")[0];
      XmlElement newElement = copyElementToName(element, "NUOVOELEMENTO");
      doc.DocumentElement.AppendChild(newElement);
}

public static XmlElement copyElementToName (XmlElement element,
string tagName)
{
   XmlElement newElement = element.OwnerDocument.CreateElement(tagName);
   for (int i = 0; i < element.Attributes.Count; i++)
   {
      newElement.SetAttributeNode((XmlAttribute)
      element.Attributes[i].CloneNode(true));
   }
   for (int i = 0; i < element.ChildNodes.Count; i++)
   {
      newElement.AppendChild(element.ChildNodes[i].CloneNode(true));
   }
   return newElement;
}