setting number of posts with query posts also exclude category title and widgets

I want to have 0 posts in some specific category pages.
So I used alternatevely the following codes:

1) in functions.php
if(!is_category(array( ‘cat ID or name’ ))) {
query_posts(‘posts_per_page=0’);
2) in archive php
<?php if(!is_category(array( ‘cat ID or name’ ))) : ?>
<?php itx_loop();?>
<?php endif; ?>

The problem is that in both cases also the category page title and all my widgets disappear: I’d like them to still be there!
Please let me know what i should to…