Trasforming this code

Dear, I use WP 2.5.1.
I’m reading (on the codex section) how to create Static Page with Mini-Loop. I found this code:

<?php
  define('WP_USE_THEMES', false);
  require('./wp-blog-header.php');
  get_header();
?>
<div id="content" class="narrowcolumn">
<h1>Welcome to my site</h1>
<p>Hello and welcome to my site. You can go to my web page about how to improve your
shoots with your digital camera; or you can go to my blog</p>

<h2>Latest posts in my blog:</h2>

<?php
  # Here starts Mini Loop trick: You can use this code, but _at your own risk_
  # If you want to improve this code, you're welcome ;)
  $how_many=7; //How many posts do you want to show
?>
<ul class="whats-new">
<?php
  $news=$wpdb->get_results("SELECT ID,post_title FROM $wpdb->posts
    WHERE <code>post_type</code>=\"post\" AND <code>post_status</code>= \"publish\" ORDER BY <code>post_date</code> DESC LIMIT $how_many");
  foreach($news as $np){
    printf ("<li><a href=\"index.php?p=%s\">%s</a></li>", $np->ID,$np->post_title);
  }
?>

</ul></div>
<?php
  get_sidebar();
  get_footer();
?>

I would like to set just a category to be seen. How can I do this?
I think I’d have to add something like ‘cat_ID’=NUMBER in the WHERE condition. I’ve tried but it doesn’t work.

Any suggestion?

Many thanks