Forcing a certain avatar on a usergroup

[MTGDarkness]

I want to make a certain usergroup have a certain avatar all the time. How can I do this?

I know it's a template edit to the postbit, but I don't know what to enter as a conditional...

PHP Code:

<if condition="usergroup?">
<div class="smallfont">
                    &nbsp;<br /><a href="member.php?$session[sessionurl]u=$post[userid]"><img src="http://imgbox.de/users/public/images/x9909v157.gif"  alt="Banned!" border="0" /></a>
                <else />
            <if condition="$show['avatar']">
                <div class="smallfont">
                    &nbsp;<br /><a href="member.php?$session[sessionurl]u=$post[userid]"><img src="$post[avatarurl]" $post[avwidth] $post[avheight] alt="<phrase 1="$post[username]">$vbphrase[xs_avatar]</phrase>" border="0" /></a>
                </div>
            </if></if>