My understanding is that content is weighted based on how far down the document it is - content closer to the beginning of the file is considered more important. By switching to a CSS design method, you get two advantages. You remove code overhead, that results in all your content moving a little bit closer to the beginning of the document, and you also have the ability to change the order items are displayed. For example, on my main web site, the navigation and headers which browsers render first are actually the last thing in the page. I use CSS to move these less important elements to the bottom of the file, which would not be possible in a tabled layout.

There is another issue, that might mitigate this advantage, however. Searching through Google Webmaster Help a few days ago, I found a question about the "100 link limit" that is in the webmaster guidelines. The response was that the 100 link limit was made up, based on a cache limit. Originally, the spider would only index the first 10k of a document, and over 100 links would make the document longer and some parts of the page would not be indexed. (Not sure how the two concepts really relate, myself) However, that limit has become meaningless because the limit was raised several years ago to 100k, and now spiders index (and run the discovery process) on the first 500k. Depending on the importance of a page (probably a reference to the page rank), spiders may even index documents of up to 1Mb.

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