Exclude one child category from Post display

Hey all,

I am using the code below to display the first Post from a category, but is there any way I could ammend it slightly so that one of the child categories is excluded from this?

I have tried using ‘exclude’ as an argument but it did not work.

Thanks.

<!-- Top News Story Sidebar -->
<div class="rightColItem rc_news rc_title">
      <a href="<?php echo get_permalink(67); ?>">Latest news</a>
	<?
		$post = get_posts(array('cat' => 75));
		$post = $post[0];
		$post->post_content = explode('.', strip_tags($post->post_content));
		$post->post_content = $post->post_content[0];
	?>
</div>
<div class="rightColItem rc_newsItems pinkLinks rc_bottPadding">
	<ul class="rc_linkList">
    	<li class="link_arrow"><a href="<?=$post->guid?>"><?=$post->post_title?></a></li>
    </ul>
    <p><?=$post->post_content?>. <a href="<?=$post->guid?>">Read more...</a></p>
</div>