Floating an AdSense Block - Me vs. Internet Explorer

I'm experimenting with CSS layout options to maximize CTR and CPM.

I am working with (against?) CSS on a pre-production domain, Expat Intelligence.

This page looks the way I want it to look in Firefox. However, in Internet Explorer the AdSense float isn't working as I want it to.

The AdSense block is in a CSS section called embedded, which is in another CSS section called center.

#center {
        width:570px;
}

#embedded {
        float:right;
        width:336px;
}

Code (markup):

In Firefox, embedded and center share the same horizonal space. In IE, center doesn't start until below the bottom of embedded.

The usual advice from Curing Float Drops and Wraps doesn't seem to apply.

I've tried quite a few different things, but none seem to be the right thing. This code is so simple; I am certain that I have not found a "new" IE bug. I must just be missing something fairly straightforward.

Does anyone have a clue as to what that might be?

 

I made it work by cheating. I used a table for layout.

 

Does it work if you put the embedded section before the center section in the html?