What CSS can do is pretty awesome, but as was mentioned above, IE in particular, and even some of the others have really dropped the ball on making the browsers read it right. In fact, it looks like Microsoft won't play any game unless they write the rules themselves.
If you're talking about one static page, you have to still use tables unless you want to spend 4 times as much time to get the same thing. But if you're designing a site, you should probably spend the time to get CSS implemented as it makes future alterations and updates far, FAR easier. Firefox and Mozilla and Netscape and Opera, et all are probably more likely to eventually fall in step with the standards, but I seriously doubt IE will ever be completely compliant.
Not because they can't. Just because they won't.
http://www.csszengarden.com/ has some really neat examples of how CSS can be used to great effect to change the layout and appearance of a webpage by simply changing the CSS, without even touching the index file.