I don’t think the question was about saving a div. I assume his layout is something similar to:
Of course, it’s possible to create two wrapper divs to separate out the nav, but who knows, maybe he has to work with someone else’s HTML, or maybe he just doesn’t want to change the HTML.
In any event, if absolute positioning works, there’s no reason not to use it. Whether you add a couple lines of CSS for the AP or a few lines for the extra div in markup, it’s up to you. Personally, I prefer to make design changes in the CSS if I can help it.