The user of a screen reader, as every accessibility-minded developer knows, does not want to have to search through the same top and left hand navigation before coming to the content on a site. Rather, it would be best if the visual experience of looking was somehow 'replicated', in that the text should come first on the page.
We've gone over the fact that 'tables are bad'* on many occasions, and we've all learned to seperate our content from the styling of our content.
What this means, of course, is that if the styling is removed, you are left with 'just the facts'.
Often, though, when the styling is removed, we find we are left with a list of logos, left hand navigations and copyright details, etc, before reaching the main page content. The solution is to have a 'skip navigation' link (Read Dave Child's well written article on this subject), or to use an alternate CSS layout to shove the page template information to the end of the document flow.
*There are many reasons not to use tables for layout , however tables aren't bad in and of themselves. See the chapter titled 'Tables are Evil?' in Dan Cederholm's heartily recommended 'Web Standards Solutions'. And here's a tutorial on marking up tabular data. Back to article.