[xsl] Searching text within a node

["Lee" <lee@xxxxxxxxxxxxx>]

I have a block of xml that looks like the following.

 <Form>
 <Names>
  <LastName>Jones</LastName>
  <LastName>Smith</LastName>
  <LastName>Anderson</LastName>
  </Names>
  </form>


I need to display blocks of code only if text matches the 
text in any of the three nodes(or more) in LastName. So 
you may have a block of code that should display only if 
"Jones" is in the above nodes. I've examined XSL IF and 
Choose and can't really find anything that works for this 
purpose. Thanks.