custom post type – use default or create new?

There is no need to create a new post type and remove the regular post, just rename post to work,

add_filter('gettext','rename_post_to_work');
function rename_post_to_work( $input ) {
    if( is_admin() && 'post' == $input || 'Post' == $post_type )
        return 'Work';
    return $input;
}