I remember when I first started coding, and I used tables. But, as soon as I got into CSS, I found it the way to go.
CSS is much more... fluid. You can achieve way more with css that just cannot be done with tables.
I have designed and coded tons of different sites without tables. Some people were amazed by the fact that my layouts didn't use tables.
Tables should be used to display tabular data only.
CSS is also better because it allows your site to be more accessible (WAI) to people with disabilities.
Try going to a site and checking out its structure (take off the stylesheets in your browser). With CSS, only the data is displayed, but when tables are involved for the design, there are images all over the place, which are images we don't need.