That kind of makes it work except now the center column gets pushed all the way to the left and overlaps it. Anyhow, I'm scratching my head here trying to figure it out so any input is greatly appreciated!
You need two layers. Not "layer" by name as in z-values, just two conceptual layers. The first layer divides your site into side-by-side slices, each the full height of the page. The second layer is what happens inside each of those slices.
The floats should not affect anything, since they are all floating around inside the central section.
And, ahem, you know perfectly well you are not allowed to link to your own site. In the how-to forums like CSS and HTML, this is not only for boring webmaster reasons involving green stuff. It's because the post is about the situation as it exists right now, not as it will exist in 2015 when some future searcher comes across this thread.
But as long as I'm there... MSIE 10 doesn't recognize Conditional Comments, and MSIE 9 may or may not need them. So always specify a version. And then only as an absolute last resort when you're using something that any browser with the brains of a lemming should be able to support.