how can i traverse and edit each xml node data using vb.net

Hi

Is there any code in vb.net that traverse through each and every node allow us to change on any specific. I need to traverse each node if exist and their child nodes if exist and need to modify that specific node content. e.g. US to United States
Xml sample:

 <GATE>
  <GAT>Q</GAT>
  <GA>Mon</GA>
    <DEST>
     <GR>
       <GC>15</GC>
       <GN>All</GN>
      </GR>
      <GR>
        <GC>15</GC>
        <GN>Cuba</GN>
          <DES>
            <DE>
                <DC>15</DC>
                <DN>US</DN>
            </DE>
          </DES>
      </GR>
    </DEST>
 </GATE>

Regardless of how deep the xml is ..i need to traverse each node and its child node and so on ... any vb.net code sample would help me

Thanks
Shaukat