Hide c-box from guests

[pigpog]

Hi everyone.

We're using a c-box for our chatbox which we've been using for a while and I've transplanted it over into my footer template, which is great. However, is there a code that I can use to hide it from the guest group? This is what I use to hide it from guests on my previous forum....

<span id="hidden_content" style="display: none;">
c-box code goes in here
</span>
<script type="text/javascript">
<!--
if(pb_username != 'Guest')
        document.getElementById('hidden_content').style.display = '';
//-->
</script>

I was hoping it's a simple modification of the bottom part to replace "if(pb_username != 'Guest')" with a variable for the guest group on vbulletin. If there's another code I can use altogether, then I'll take that!

So if anyone can help, it's much appreciated!

Thanks!