Bloke on "Showing first couple lines of post"

Here is my custom function that is a widget that displays the last post the category. But I need to use some PHP script to show just the first few lines of the post. Since I am not using <!--more--> tag. I need to find another way. Also you may wonder why I am using the preg_replace its because I need to remove [gallery] from showing.

function widget($args, $instance)
  {
    extract($args, EXTR_SKIP);

    echo $before_widget;
    $title = empty($instance['title']) ? ' ' : apply_filters('widget_title', $instance['title']);

    if (!empty($title))
      echo $before_title . $title . $after_title;;

query_posts('cat=10&posts_per_page=1');	

if (have_posts()) :
	while (have_posts()) : the_post();
		 the_title(); echo '<br/>';
the_post_thumbnail(apply_filters('graphene_excerpt_thumbnail_size', 'thumbnail'));
$content = get_the_content();

echo '<p span class="here">'; echo preg_replace ('/\[.*\]/', '', $content); echo '</span></p>';
	endwhile;
endif; 

wp_reset_query();

    echo $after_widget;
  }

}
add_action( 'widgets_init', create_function('', 'return register_widget("MyWidget");') );?>