title: How best to update an XML node in MSBuild
body: <p>I have been using the Tigris community tasks to update various AppSettings keys using the XMLUpdate task. </p>
  
  <p>Now, however I want to add a node to the system.net section to set up the proxy. </p>
  
  <p>I declared a property</p>
  
  <pre><code>&lt;PropertyGroup&gt;
      &lt;proxy&gt;&amp;lt;defaultProxy&amp;gt; &amp;lt;proxy usesystemdefault="False" proxyaddress="http://IPADDRESS:PORT" /&amp;gt; &amp;lt;/defaultProxy&amp;gt;&lt;/proxy&gt;
    &lt;/PropertyGroup&gt;
  </code></pre>
  
  <p>and the XMLUpdate Task looks like </p>
  
  <pre><code>&lt;XmlUpdate
   Prefix="n"
   Namespace="http://schemas.microsoft.com/.NetConfiguration/v2.0"
   XmlFileName="$(BuildDir)\Builds\_PublishedWebsites\Presentation\Web.config"
   XPath="/n:configuration/n:system.net"
   Value="$(proxy)"  /&gt;
  </code></pre>
  
  <p>this updates the web config however it updates directly from the property group i.e. doesn't convert the escape characters for the angle brackets. Does anyone have any ideas? </p>