Popup invitacion al registro

[el_arenas]

el caso es que ya logre encontrarlo, pero me sale siempre, y lo que quiero es que salga solo cuando los usuarios no estan registrados y no soy capaz de lograrlo, tengo un foro phpbb3 a ver si alguien es capaz de entender lo que quiero.
Un saludo

Código:

 <if condition="$show[guest]">
 <!-- Improve registration Rates -->
<style type="text/css">

#topbar{
    position:absolute;
    border: 0px solid black;
    padding: 5px;
    background-color: ;
    width: 500px;
    visibility: hidden;
    z-index: 200;
    top: 27px;
    height: 134px;
    left: 13px;
}
img {
    border: none;
}

</style>

<script type="text/javascript">
var persistclose=0 //set to 0 or 1. 1 means once the bar is manually closed, it will remain closed for browser session
var startX = 30 //set x offset of bar in pixels
var startY = 5 //set y offset of bar in pixels
var verticalpos="fromtop" //enter "fromtop" or "frombottom"

function iecompattest(){
return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
}

function get_cookie(Name) {
var search = Name + "="
var returnvalue = "";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search)
if (offset != -1) {
offset += search.length
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
returnvalue=unescape(document.cookie.substring(offset, end))
}
}
return returnvalue;
}

function closebar(){
if (persistclose)
document.cookie="remainclosed=1"
document.getElementById("topbar").style.visibility="hidden"
}

function staticbar(){
barheight=document.getElementById("topbar").offsetHeight
var ns = (navigator.appName.indexOf("Netscape") != -1) || window.opera;
var d = document;
function ml(id){
var el=d.getElementById(id);
if (!persistclose || persistclose && get_cookie("remainclosed")=="")
el.style.visibility="visible"
if(d.layers)el.style=el;
el.sP=function(x,y){this.style.left=x+"px";this.style.top=y+"px";};
el.x = startX;
if (verticalpos=="fromtop")
el.y = startY;
else{
el.y = ns ? pageYOffset + innerHeight : iecompattest().scrollTop + iecompattest().clientHeight;
el.y -= startY;
}
return el;
}
window.stayTopLeft=function(){
if (verticalpos=="fromtop"){
var pY = ns ? pageYOffset : iecompattest().scrollTop;
ftlObj.y += (pY + startY - ftlObj.y)/8;
}
else{
var pY = ns ? pageYOffset + innerHeight - barheight: iecompattest().scrollTop + iecompattest().clientHeight - barheight;
ftlObj.y += (pY - startY - ftlObj.y)/8;
}
ftlObj.sP(ftlObj.x, ftlObj.y);
setTimeout("stayTopLeft()", 10);
}
ftlObj = ml("topbar");
stayTopLeft();
}

if (window.addEventListener)
window.addEventListener("load", staticbar, false)
else if (window.attachEvent)
window.attachEvent("onload", staticbar)
else if (document.getElementById)
window.onload=staticbar
</script>




<div id="topbar">
<p align="right"><a href="" onClick="closebar(); return false"><img src="RUTA DE LA IMAGEN PARA CERRAR EL POP UP" border="0" /></a>
  </align>
<a href="http://www.TUPAGINA.COM/FORO/register.php"><img src="RUTA DE LA IMAGEN POP UP"></a></td>
</div>

<!-- End Improve Registration -->
 </if>