Aligning elements next to each other

Hello:

I’m using a modified style template and have created a few new elements for my side. My latest addition is what I call “bannerbar” and will serve to display banner ads. Everything worked great but now – depending on where I place the <div id=”bannerbar”> command line in the template.php it either displays below or above the other elements (div sidebar and div content). The width and margins should all work out right next to each other, so I have no idea what is going on.

Please check it out and let me know if you have any ideas:
http://www.smarteeconsulting.com/?page_id=18

Thanks!