easy one: how to parse PHP code on page gen?

[webghey]

OK so I have a forum and I'm trying to modify my ad column. Basically I can edit the code for this column, which is similar to this:

<br />
<table cellpadding="$stylevar[outerborderwidth]" cellspacing="0" border="0" class="tborder" width="$stylevar[tablewidth]" align="center">
	<tr>
		<td>
<table cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" style="width:100%">
	<tr align="center">
		<td class="tcat"><span class="smallfont"><b>Advertisement</b></span></td>
	</tr>
	<tr>
		<td class="alt1" align="center">


		<!-- ads go here -->

</td></tr></table></td>
	</tr>


</table>

Note the "ads go here" html comment.

So I'd like to include a PHP script I wrote which will (for the sake of info here) randomly rotate a few ads. Easy script, no big deal.

<?php require("/forums/random.php"); ?>

Obviously the result of putting this in the above HTML code/template is that the PHP is not parsed. I imagine this is due to post-PHP/outside-of-PHP parsing which occurs when a page is generated with vbulletin eh?

Is there a work around for this, or will I need to resort to rewriting my handy script in javascript?

Any help is appreciated!! =)