Conditional codes: Ads

[Xtrigit]

Hello, everyone!

Say I have 3 categories(forums)

I want to display a banner on cat. 1 and 2 (Showthread only)

If a guest visits the third categorie(forum), he should see a different banner.

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also, I have a banner that will float everywhere on the site, I pasted the code in the footer;

this is the conditional I'm using:
<if condition="in_array($bbuserinfo[usergroupid],array(6,7,5,9))">leave this empty to not show ads to admins+mods<else />
Guests will see BANNER</if>

How can I modify this conditional so that it won't show ads in a particular category? (forumdisplay + showatread) ?

Thanks