Here is a mockup of how the page should work. It's "pretty much done" except for "D" and "E" on the mockup. "D" has a right margin and "E" (a fixed width area) is floated in that margin, which of course means it's not in the flow, so it's not forcing "D" to get taller when it has more content than "D". "D" has a blue background that needs to fill in - "D" is fluid and I will never know it's dimensions.
For now, to get this done I've had to make D+E a table to get the desired effect. Maybe if D and E were percentage widths I wouldn't need to float E? I think E floating is the problem...
edit: FYI, I cannot use absolute position in this except in an instance like a skipnav where that declaration is used to simply take something out of the flow, not to actually position it.