Show all products in category on productinfo page

[goosedesign]

Does anyone know how I might achieve this? What I'm looking for is that on each individual product page (tpl_product_info_display.php), there is also a list, much like you would see on a category page (tpl_modules_product_listing.php) with just thumbnails of each product in the same category as the current main one.

I've tried just pasting the following in to tpl_product_info_display.php, but get the error:
"1109 Unknown table 'p' in field list
in:
[select count(p.products_id) as total ]"

<?php
 include(DIR_WS_MODULES . zen_get_module_directory(FILENAME_PRODUCT_LISTING));
?>
<div id="productListing">
<?php
/**
 * load the list_box_content template to display the products
 */
  require($template->get_template_dir('/tpl_grid_display.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_grid_display.php');
?>
</div>

Many thanks!