title: `attr('checked', false)` not working on IE6
body: <p>As the title says, I can't get <code>.attr('checked', false)</code> to work on IE6. I am cloning some HTML and then before I assign the newly cloned HTML to a element, I run through it and un-check all of the checkboxes that are in the newly cloned section, which works fine in all browsers except IE 6. </p>
  
  <p>Here is the code:</p>
  
  <pre><code>    //give each input and select a custom id
      clone.find('input, select').each( function( i ) {
  
              //get the id attribute
              var id = $(this).attr('id');
  
              //uncheck all of the tick boxes
              $(this).attr('checked', '');
  
              //get the name attribute
              var name = $(this).attr('name');
  
              $(this).attr('name', name+"_"+count)
              $(this).attr('id', id+"_"+count+"_"+i)
  
      });
  
      //append the newly created area to the area wrapper
      clone.appendTo('[data-custom="area_wrapper"]');
  </code></pre>
  
  <p>Is there any way that I can work around this problem?</p>