title: C# backwards compatibility
body: <ol>
  <li>I am using windows 7 running .net 4.0</li>
  <li>I wrote an application on my platform then distributed it to my coworkers.  </li>
  <li>They are   using windows XP .net 3.0 and 3.5</li>
  <li>They can not update to .net 4 for business reasons.</li>
  <li>I am running Visual studio 2010</li>
  </ol>
  
  <p>How can i make my application backwards compatible so that they can use it?</p>