Group by "Additional Categories"

[Senkusha]

Hi, I needs some help with the product query.  Here's what I want to do:

If you've been to my store, you'll know that I've grouped each product in it's own category (named by the anime series title), and then I've added the additional category for the type of product it is.  So for example, what I'd llike is a break down like this (If I click on Ah My Goddess, I'll get)

Ah My Goddess
  DVD's:
{some products}

  Manga:
{some products}

  Books:
{some products}

  Accessories:
{some products}

However, if I click on DVD's I want the listing to be broken down by Primary Category (like the following)

DVD's
  Ah My Goddess
{some products}

  Azumanga Daioh
{some products}

  Happy Lesson
{some products}
...

I thought just by adding a GROUP BY was sufficient enough, but, it's not.  Do you have any suggestions for me?

Thanks!

[SMFHacks]

What do you have so far for the query?