To enable that in Firefox (and in Opera 9) replace original code with following:
Code:
<if condition="$show['avatar']">
<div class="smallfont">
<br />
<a href="member.php?$session[sessionurl]u=$post[userid]"><img src="$post[avatarurl]" alt="<phrase 1="$post[username]">$vbphrase[xs_avatar]</phrase>" border="0" style="filter:alpha(opacity=200); opacity: 0.2;" /></a>
</div> </if>