File

<?php

    $m_slider_sort = get_option('sort'); if(empty($c_slider_sort))    {$c_slider_sort = "post_date";}
    $m_slider_order = get_option('order'); if(empty($c_slider_order)){$c_slider_order = "DESC";}
    $m_slider_post_limit = get_option('limit_posts'); if(empty($m_slider_limit_posts)){$m_slider_limit_posts = "-1";}

    global $wpdb;

    global $post;

    $args = array( 'meta_key' => 'feat_music', 'meta_value'=> '1', 'suppress_filters' => 0, 'post_type' => array('post', 'page'), 'orderby' => $m_slider_sort, 'order' => $m_slider_order, 'numberposts'=> $m_slider_post_limit);

    $myposts = get_posts( $args );

   $i=0;
   foreach( $myposts as $post ) :  setup_postdata($post);
    $i++;
    if ($i=1) { 
         echo '<div class="first-post>';
         { do your thing for the first post }
         echo '</div>';
    else { ... }
    }

        $m_slider_custom = get_post_custom($post->ID);

        $m_slider_thumb = m_slider_get_thumb("featmusic");

    ?>


<?php endforeach; ?>