A quick follow up: If I only want to show the ads to visitor and also "regular" members, but not to paid members, how would the code be edited? For example:
Show ads only to visitor and members, but not to "premium members"
How can I hide content from a specific user group? <xen:if is="!{xen:helper ismemberof, $visitor, x}"> This content will be hidden from members of user group x
</xen:if>