@civilz– $count shouldn’t be in quotes, and you don’t have to echo it. You might want to try the format below for query_posts. It is more clear and readable.
One other thing, $count = $theme_options['count_nabz'] is probably an array. You can see this by typing print_r($count);
So the full code should be:
$theme_options = get_option('my_theme_settings');
$count = $theme_options['count_nabz'];
$count = $count[0];
$args = array(
'cat' => 2,
'posts_per_page'=> $count
);
query_posts( $args );