You can modify the template used for it however you want
The template tag which generates the html in the sidebar is to be found in wrapper.html ( {$premium_list} )
Now you could for example place that before {$content} so it shows up before rank 1.
Then open up premium_list_row.html and modify the html, so remove the screenshot etc for example and just having a list of banners would go like this
Code:
<a href="{$url}" onclick="out(this,'{$username}');"><img src="{$premium_banner_url}" alt="{$title}" title="{$lng->g_premium_visit}" class="vistip"/></a><br />