Showing sub categories

Hiya all,

I've got two menus on my pages - a main menu across the top of the page and the sub menu down the right hand side.

So, I can use the example code given for the category menu to display the menu across the top but the minute I add a sub-menu it obviously tries to display that.

I've tried putting "where -> parentNum = 0" in the code but that just breaks it, so how can I acheive this?

Also, how can I display the sub-pages to the chosen parent?

Here's the page I'm trying to acheive:

http://bentley.cogress.co.uk/page.php?Knowledge-2

Any pointers would be really helpful!