People who are stuck in "Table Head" are going to get left behind as more and different devices access the internet. It's already happening with mobile phones, palm pilots and screen readers. If you are doing business of any sort on the web you need to get with the program, otherwise you are purposely leaving out a significant percentage of your audience, who, if your site won't load on their alternative device, will simply go to your competitor's site.
All the layout cross browser "problems" have been solved. There is really no excuse to use an outmoded, outdated and backwards thinking way of coding if you're heading into the future with a redesign. And though more than one person has stated that it doesn't make a difference to
SEO, that doesn't mean it won't in the future.
Google Webmaster Guidelines suggest using valid html. They also suggest looking at your site in the Lynx browser since that's the way spiders see your site.