parse responseText or responseXML

Dear Friends,

I am getting response from an Ajax call to a webservice.The response is of two types
i.e responseText and responseXml.
My webservice is just returning a small string as this - POINT(73.7234375 25.151953125).
Now when I see responseText it is coming something very huge with HTML tags.

Now when I see responseXML it is coming like this:

 <?xml version="1.0" encoding="utf-8" ?>
  <string xmlns="http://tempuri.org/">POINT(73.7234375 25.151953125)</string>

But when I try to parse the ROOT Node and get its value I am unable to get it - I get only errors.

So how to get the value using responseXML and responseText.

My code is as below:

//  function where response from Ajax call is obtained.

function state_Change() {
      if (req.readyState != 4) return;
   & ...