You can use StreamReader to get the response as text....
httpResponse = (HttpWebResponse^)httpRequest->GetResponse();
StreamReader^ reader = gcnew StreamReader (httpResponse->GetResponseStream());
string^ textData = reader->ReadToEnd();
// To parse the xml data (to get the value 200 in <response>200</response>)
XmlDocument^ doc = gcnew XmlDocument;
doc->LoadXml( textData );
XmlNode^ root = doc->DocumentElement;
XmlNode^ node = root->SelectSingleNode( "response" );
String^ responseValue = node->InnerText;
Hope this helps.