[Revelence]

If you're trying to just rotate the banner, you can make a plugin. Here's a plugin that should work.

ob_start();
	$banners 	= array('banner_1', 'banner_2', 'banner_3');
	$rand 		= rand(0, count($banners) - 1);
	echo $banners[$rand];
	$php_include = ob_get_contents();
ob_end_clean();
vB_Template::preRegister('header',array('random_image_background' => $php_include));

Now edit your header template of your theme. Search for where ever the logo is being called at, and replace

<img src="blablabla" />

with

<img src="{vb:raw random_image_background}" />

Replace the banner_1, banner_2, and so on with your banners. You can add more then 3, and you don't need more then 1.