<?xml version="1.0" encoding="windows-1251"?>
<soapenv:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope">
<soapenv:Header/>
<soapenv:Body>
  <ws:GetCoordResponce>
   <ObjectID> 123 </ObjectID>
   <Coord time="2011-01-29T11:30:01Z" lon="36.757689" lat="51.666458" speed="43.2" dir="30" valid="1"/>
  </ws:GetCoordResponce>
</soapenv:Body>
</soapenv:Envelope>

XmlDocument soapEnvelopeXml = new XmlDocument();
soapEnvelopeXml.LoadXml("<?xml version='1.0' encoding='windows-1251'?>" +
"<soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/'>" +
"<soapenv:Header/>" +
"<soapenv:Body>" +
"<ws:PutCoord xmlns:ws='http://www.w3.org/2001/XMLSchema'>" +
"<ObjectID>" + Data[ 0 ] + "</ObjectID>" +
"<Coord time='" + Data[ 2 ] + "' lon='" + Data[ 4 ] + "' lat='" + Data[ 3 ] +
"' speed='" + Data[ 5 ] + "' dir='" + Data[ 6 ] + "' valid='" + Data[ 7 ] + "'/>" +
"</ws:PutCoord>" +
"</soapenv:Body>" +
"</soapenv:Envelope>");
using (Stream webstream = webRequest.GetRequestStream())
    soapEnvelopeXml.Save(webstream);
IAsyncResult asyncResult = webRequest.BeginGetResponse(null, null);
asyncResult.AsyncWaitHandle.WaitOne();