The following code worked for me, put it in your theme's template.php and replace theme with the name of your theme:

function theme_preprocess_comment(&amp;$vars) {
  $element = $vars['elements'];
  $comment = $element['#comment'];

  if(array_key_exists('#entity_type', $element) &amp;&amp; $element['#entity_type'] == 'comment') {
    $vars['classes_array'][] = $comment-&gt;uid == 1 ? 'answer' : 'question';
  }
}


Although I think the extra checks for entity type is not necessary since this theme is only applied to comments.

How to add classes to comments?
I have 2GB of RAM on my laptop, which is the max.  

Should I install 32 bit version or 64 bit version?
