How about putting this script in your ad section?
It rotates the banner with each pagerefresh, and you can add as many banners as you want.
Compatible with all versions becouse it is just basic javascript.
Code:
<script language="JavaScript">
images = new Array(4);
images[0] = "<a href = 'http://www.LinkToBannersWebsiteA.com' target='_blank'><img src='http://www.PlaceWhereTheBannerIsStored_a.gif' alt='ALT text'></a>";
images[1] = "<a href = 'http://www.LinkToBannersWebsiteB.com' target='_blank'><img src='http://www.PlaceWhereTheBannerIsStored_b.gif' alt='ALT text'></a>";
images[2] = "<a href = 'http://www.LinkToBannersWebsiteC.com' target='_blank'><img src='http://www.PlaceWhereTheBannerIsStored_c.gif' alt='ALT text'></a>";
images[3] = "<a href = 'http://www.LinkToBannersWebsiteD.com' target='_blank'><img src='http://www.PlaceWhereTheBannerIsStored_d.gif' alt='ALT text'></a>";
index = Math.floor(Math.random() * images.length);
document.write(images[index]);
</script>