Funnily enough, I'm a designer....
I can work either way, with tables or css, or both. It depends on the job. It's like, do you use .html or .php extensions on your pages, I think a little variety covers all bases.
I've tested both table sites and css sites on Google and the sites complying with xhtml do a little better, but it's not a majorly significant edge. There are far too many other factors involved.
My main concern is making sure sites work cross platform. But it's only recently that I've seriously looked into dropping tables... perhaps because it's trendy?
"Coded like it's 1999"
I think more people should test sites using IE, Firefox, Safari, Opera, Chrome, etc... the browsers are the main yardstick.