This is an interesting thread. I am somewhat of a novice, but I had always though that you wanted to put a headers first, then nav, then content. unless the document itself only contains content about one subject ( as of yet I have never had to do a page like that). readers/screen readers will always have to sift to something, no? One would figure it would be quicker to go through a header/navigation and confirm you are where you want to be, than have to sit through content that turns out NOT to be what you desired, before you can get to way to navigate towards what you want.