Show only posts from specific category wih pagination

Hello,
i have the code below and i need to customize so hen a user clicks on category A he sees all and just the posts from that category , if they click on category b they see posts just from that category….i want to set it to show just 3 posts as well with a pagination option ….i have the pagination done its just the showing specific category posts that is an issue…any help from the wp community ??

<?php
get_header();?>

<!-- MAIN -->
<div id="main">

<!-- Content area -->
<div class="content">

    <!-- LeftPart -->
    <div id="leftPart">

        <?php
        $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
        query_posts("showposts=5&paged=".$paged);
        while(have_posts()):the_post();
        ?>

        <?php in_category( $category, $_post ) ?>
        <!-- Blog Entry -->
        <div class="blog_entry">
            <!-- Inside -->
            <div class="inside">

                <div class="date"><?php the_time('F l, Y'); ?> at <?php the_time('g:i a'); ?> </div>
                <div class="comments"><?php echo get_comments_number();?></div>
                <br class="clear" />

                <h3><a href="<?php the_permalink();?>"><?php the_title();?></a></h3>

                <?php
                $attr = array('class'	=> "one_col_shadow_img");
            	the_post_thumbnail('blogs',$attr);?>
                <p class="biglines"><?php echo get_the_excerpt();?></p>

                <a href="<?php the_permalink();?>" class="arrow_read"><span class="inv">Read more</span></a>

            <br class="clear" />
            </div>
            <!-- /Inside -->
        </div>
        <!-- /Blog Entry -->

        <?php endwhile; paginator(); ?>

        <br class="clear" />

    </div>
    <!-- /LeftPart -->

    <!-- Sidebar -->
    <div id="sidebar">
        <!-- Inside -->
        <div class="inside">

        <?php get_sidebar();?>

        </div>
        <!-- /Inside -->
    </div>
    <!-- /Sidebar -->

    <br class="clear" />

</div>
<!-- /Content area -->

<!-- Main bottom [ DO NOT REMOVED ] -->
<div id="main_bottom" class="main_bottom_<?php echo get_option('zombie_designtype',true);?>">
    <div class="content"></div>
</div>
<!-- /Main bottom -->
</div>
<!-- /MAIN -->
<?php get_footer();?>