Excluding categories from popular posts

I have a function that displays the top 5 popular posts, but I need to remove categories from it so they don’t appear in the popular posts section. The code is…

function wp_popular_posts($pop_posts = 5 , $thumb = true){
	global $wpdb , $post;
	$orig_post = $post;

	$popularposts = "SELECT ID,post_title,post_date,post_author,post_content,post_type FROM $wpdb->posts WHERE post_status = 'publish' AND post_type = 'post' ORDER BY comment_count DESC LIMIT 0,".$pop_posts;
	$posts = $wpdb->get_results($popularposts);
	if($posts){
		global $post;
		foreach($posts as $post){
		setup_postdata($post);?>

Then it goes on to print out the post. I wanted to know if there’s an easy way to exclude certain categories within this??

I know about query_posts(cat=-4) but not sure if I could use that method here? if so where should I put it?

Any help is appreciated, thanks in advance!