Displaying Posts Using a Custom Select Query

I am using the following code to pull a list of posts

<?php

 $querydetails = "
   SELECT wposts.*
   FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
   WHERE wposts.ID = wpostmeta.post_id
   AND wpostmeta.meta_key = 'showscore'
   AND wpostmeta.meta_value = 'YES'
   AND wposts.post_status = 'publish'
   AND wposts.post_type = 'post'
   ORDER BY wposts.post_date DESC
 ";

 $pageposts = $wpdb->get_results($querydetails, OBJECT)

 ?>

What I would like to do is have more than one list on the page. Each list needs to be defined by category. How do i make the above code only pull post from one category?
I found a line of code on this page and tired inserting it and broke my list

AND $wpdb->post2cat.category_id IN (48)

Can someone help ??

Thanks allot

Steve