[Lynne]

Default vb code checks to see if there is a custom avatar and sets show[avatar] to true if there is so that the image code is only shown if it exists. So, have you tried just using that code with an else statement for the default avatar:

<if condition="$show['avatar']"><td class="alt2"><a href="member.php?$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></td>
<else />
your default avatar
</if>