have_posts() returning true when it should be false

I have read that multiple loops and that is where I read:

The have_posts() simply calls into $wp_query->have_posts() which checks a loop counter to see if there are any posts left in the post array. And the_post() calls $wp_query->the_post() which advances the loop counter and sets up the global $post variable as well as all of the global post data. Once we have exhausted the loop, have_posts() will return false and we are done.

Which gave me the impression that calling have_posts() would not affect the anything. Only the_post() will move the counter forward.

But let me describe what I am doing. I am new to WordPress and I did a lot of reading so I am familiar enough to get myself into this current mess.

For my theme, the index.php page loads a custom header header('blog'); and I use the first post to populate the header.

Before starting the “loop” in the main body of index.php I use the rest of the first post to populate some fields and then advance forward using the_post().

Here is my code:

<?php get_header(); ?>

            <?php /* if there is a post add the post title to the header */
            get_header('blog'); ?>

            <div class="main">
              <?php get_sidebar(); ?>
	            <div class="blog-main-content">

	            <?php /* if there is a post then its title has already been added to the header. my attempt to fix the have_posts() problem. */
	            rewind_posts();
	            if (have_posts()) : the_post(); ?>

	            <div <?php post_class() ?> id="post-<?php the_ID(); ?>">				        

				        <div class="first-entry">
				          <?php the_content('Read the rest of this entry &raquo;'); ?>
				        </div>

				        <p class="postmetadata"><?php the_tags('Tags: ', ', ', '<br />'); ?> Posted in <?php the_category(', ') ?> | <?php edit_post_link('Edit', '', ' | '); ?>  <?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?></p>

				      </div>

/*This part is interesting.  I have only one post for my test data and this check returns false as expected*/

<?php if (have_posts()) {   ?>
			          <hr />
			        <?php } ?>

/*But this check then returns true*/

<?php while (have_posts()) : the_post(); ?>

      <div <?php post_class() ?> id="post-<?php the_ID(); ?>">
        <h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
        <p class="post-date"><?php the_time('F jS, Y') ?> <!-- by <?php the_author() ?> --></p>

        <div class="entry">
          <?php the_content('Read the rest of this entry &raquo;'); ?>
        </div>

        <p class="postmetadata"><?php the_tags('Tags: ', ', ', '<br />'); ?> Posted in <?php the_category(', ') ?> | <?php edit_post_link('Edit', '', ' | '); ?>  <?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?></p>

      </div>
      <?php if (have_posts()) { ?>
          <hr />
        <?php } else {
                break;
             }
        ?>

    <?php endwhile; ?>

    <div class="navigation">
      <div class="alignleft"><?php next_posts_link('&laquo; Older Entries') ?></div>
      <div class="alignright"><?php previous_posts_link('Newer Entries &raquo;') ?></div>
    </div>

  <?php else : ?>

    <h2 class="center">Not Found</h2>
    <p class="center">Sorry, but you are looking for something that isn't here.</p>
    <?php get_search_form(); ?>

  <?php endif; ?>

	            </div>
            </div>

<?php get_footer(); ?>