Also thought I should add this just in case anyone else is wanting to do something similar

The above will stop those products appearing on your "New Products" Page

However it will not prevent the products appearing in the "New Products for Month" section of your page, if you have this turned on


As the category that I wanted to hide the products of, was a top level category, these product were also appearing on my main page in the "New Products for Month" section to prevent this I changed this

Code:
if ( (!isset($new_products_category_id)) || ($new_products_category_id == '0') ) {
  $new_products_query = "select p.products_id, p.products_image, p.products_tax_class_id, p.products_price, p.products_date_added
                           from " . TABLE_PRODUCTS . " p
                           where p.products_status = 1 " . $display_limit;
} else {
to this

Code:
if ( (!isset($new_products_category_id)) || ($new_products_category_id == '0') ) {
  $new_products_query = "select p.products_id, p.products_image, p.products_tax_class_id, p.products_model, p.products_price, p.products_date_added
                           from " . TABLE_PRODUCTS . " p
                           where p.products_model != 'HIDE'
                           and p.products_status = 1 " . $display_limit;
} else {
on the includes/modules/pages/new_products.php file (around line 18)
and saved the file as
on the includes/modules/pages/my_template/new_products.php where my_template is the name of your template

edit: remember I am using version 1.3.7

By doing it this way the "hidden" products won't ever appear on the main page in the "New Products for Month" heading, but they will still appear under that heading when i am inside the category that contains them.

Cheers