I have a different page for each category. This is what I use on the main page:
<?php $wp_query->set( 'category_name', 'worthless' ); ?> and it works just fine. But when I try using it on any other page I get a 404 error when I use the previous/next links. Right now I'm using this on every page but the main page:
<?php query_posts( '' ); ?>
<?php query_posts('category_name=thinking'); ?> and it isn't working either.