string st = null;
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(@"<?xml version='1.0' encoding='utf-8' ?> 
            <root> 
                  <property name='R1' value='' /> 
                    <property name='R2' value='' /> 
                    <property name='R3' value='' /> 
            </root>
            ");
            int i = 0;
            string res = null;
            using (StreamReader SR = new StreamReader(@"C:\temp\1.pqs", System.Text.Encoding.UTF8))
            {
                while (SR.Peek() >= 0)
                {
                    st = SR.ReadLine();                    
                    string s = st;
                    byte[] b = System.Text.Encoding.UTF8.GetBytes(s);
                    byte[] bb = System.Text.Encoding.Convert(System.Text.Encoding.UTF8, System.Text.Encoding.GetEncoding(1251), b);

                    string ansi_str = System.Text.Encoding.GetEncoding(1251).GetString(bb);
                    System.String ss = ansi_str;
                    StreamWriter SW = new StreamWriter(@"c:\temp\" + i.ToString() + ".txt", true, System.Text.Encoding.GetEncoding(1251));
                    SW.WriteLine(ss);
                    SW.Close();                    

                    doc.DocumentElement.ChildNodes[i].Attributes["value"].Value = ss;
                    i++;
                }
                doc.Save(@"c:\temp\1.xml");
            }

        }

  st = SR.ReadLine();
  SB.AppendLine(System.Text.Encoding.GetEncoding(866).GetString(System.Text.Encoding.Default.GetBytes(st)));