I'm not sure which IE/Win I'm viewing it on, but it's probably not IE6. It's doing fine on IE/Mac, netscape, firefox, and safari. Big surprise that IE/win is the sore thumb.
First, the background of the center column is stretching out to it's parent div (wrapper).
Second, every time there is something funky in the center column ("Lorem ipsum" works just fine) the column breaks and goes below the two other columns.