wordpress: using timthumb example

using timthumb

<div class="span3 " id="<?php echo $post->ID; ?>">
            <div class="" style="margin-left:0px;">
                <h2 class="entry-title"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
                <div class="postimg" id="img_<?php echo $post->ID; ?>">
                    <?php
                    if(has_post_thumbnail()) { ?>
                        <?php //echo get_the_post_thumbnail($post->ID, array(255,90)); ?>
                        <img src="<?php bloginfo('template_directory'); ?>/wp-content/themes/mytheme1/timthumb.php?src=<?php echo get_image_url(); ?>&amp;h=90&amp;w=255&amp;zc=1" alt="<?php the_title(); ?>"/>
                        <?php } else {
                            echo '<img src="'.get_bloginfo("template_url").'/images/nothumb.jpg"  alt="No Thumbnail"/>';
                    }?>
                </div>
                <div class="" id="content_<?php echo $post->ID ?>">
                     <?php echo truncateWords($post->post_content)."..."; ?>
                </div>
            </div><!--span12-->

        </div><!--span4-->