Some banner troubles, help please?

[znightmare]

Ok so because I couldn't fit my banner to all resolutions by using vbulletin's standard title image banner I just split my banner into 3 pieces and put the codes into my header template like this

<div id="banner">
<div id="ban_03"><a href="http://anime-forum.net/forum.php"><img src="images/ban_03.gif" border="0" alt=""></a></div>
<div class="clear"></div>
<div id="ban_01"><a href="http://anime-forum.net/forum.php"><img src="images/ban_01.gif" border="0" alt=""></a>
  

</div>

</div>

<div class="above_body"> <!-- closing tag is in template navbar -->
<div id="header" class="floatcontainer doc_header">

<vb:if condition="$stylevar['titleimage']"><div><a name="top" href="{vb:link forumhome}" class="logo-image"><img src="" alt="" /></a></div></vb:if>

	<div id="toplinks" class="toplinks">

And I added the appropriate css to my additional css like this...

#banner { 
background-image:url('images/ban_02.gif');
width:100%;
height:120px;
}

#ban_01 { 
float:left;
width:455px;
height:120px;
}

#ban_03 { 
float:right;
width:679px;
height:120px;
}

.clear { clear:left; }

My question is, is there a way for me to make a random banner code so that I get a different banner loaded with each refresh of the page when I have things set up like this?
I would really appreciate an answer.

edit: my url is http://anime-forum.net if it helps