I don't remember where did I read the solution on this topic. But basically, if you go to your admin page and click on the Presentation > Theme Editor, then you will see a list of php files on the right side. Click on the 'Header' link and it will bring up header.php. In this header file, you will see:
<div id="leftside">
bunch of code lines like this;
----
----
</div>
You can select a place there to experiment with your adsense placement.
I use the same theme, and I have moved for example the Featured Sites and even Calendar to the left sidebar. However, since I'm not an expert in this field, please try it with your own risk. :-)
Good luck
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