Tableless designs are always better. The benefits of tableless designs are as follows:

Reduce web page download time

Convert your web site to CSS design and reduce your web site size by 2 to 5 times. This means the download time will at least decrease by two times or more (depending on the amount of images you have).

* tables occupy from 20% to 80% more code real estate than simple, correct HTML markup: this reduces the web site size, download and customer waiting time
* as browsers display anything in a table after they scan it twice, it takes a lot of time to load a table (especially those used for design purposes)
* also, the CSS files are cached on a server, but tables in HTML files are not - the browsers load them again every time they see them

Edit your site easily

Design your site with CSS and maintain your site easily by adjusting just one file to change the appearance of a single element throughout the whole site.
Make your web site screen size friendly

Bandwidth & Rendering

Tableless design means less bandwidth. If you link in a CSS file, a browser will cache it on 1st load of a page and on further navigation only page structure itself is being downloaded. In addition to traffic cuts it significantly reduces page latency as well.

Accessibility

Prioritizing Cascading Style Sheets will also ease the process of porting a site to various platforms, e.g. mobile phones, handhelds, etc. or usage, e.g. printing. Not to mention making the site reachable for a screen reader or braille device.

Maintenance

With CSS site layout is kept apart from its structure and is centralized. That makes site design a lot easier to change. For example changing 1 single digit in CSS may increase or decrease font size of an headline on each and every page of a site.
CSS is a reusable resource as opposed to the inline definitions of HTML.

Naturally, when it comes to tables, one often comes across such an issue as fixed widths, heights or font sizes. Implement CSS and you get a web site, which will fit the browser window on any screen resolution. Also, it's font will increase or decrease if your visitor adjusts his browser settings (does not happen with fixed font sizes [px]).
Increase your web site usability and acessibility

Get Cascading Style Sheets for various media (screen, print, mobile, aural, tv, etc) to make your web site usable and accessible for even more visitors.