In order for the float left to work, you’d need all 3 columns floated left. Try this: leave your wrap set to 2000px, float the sidebar Left and also float the main-column left. The sidebar should snap to the right of the main column right up top. (remember to remove your large negative top margin. ) if you floated your second sidebar left it should float to the right of that as well.
I’d suggest that you look at the 960 grid system and use it as a prototype for this layout, it floats each column to the left like I suggested. It takes a few minutes to understand, but becomes a great prototyping resource.http://www.960.gs
this was typed from my iPhone so please excuse any typing errors that may have occured.