Help With XMLHTTP

Wonder if someone can help me please.

I am starting out in the world of XML and am dabbling with the use of XMLHTTP.

This is what I have so far -

<%

Dim objXMLHTTP, xml

Set xml = Server.CreateObject("Microsoft.XMLHTTP")

xml.Open "GET", "http://#*$!xxxxxxxxxxxx/" & keyword & "", False

xml.Send

Response.Write xml.responseText

Set xml = Nothing
%>

What I want to do is -

In the resulting text/code that gets pulled, replace "xxxx/xxxx" with "yyyy/yyyy".

I just can;t seem to crack it. Any help would be much appreciated.