[Lynne]

No, that is incorrect. You would want to do this:

<td class="alt1"><if condition="is_member_of($bbuserinfo, x,y)">
<!-- content only shown to members of usergroupid x or y -->
$forum[threadcount]
<else />
-
</if></td>
        <td class="alt2"><if condition="is_member_of($bbuserinfo, x,y)">
<!-- content only shown to members of usergroupid x or y -->
$forum[replycount]
<else />
-
</if></td>