If you want to be technical about it... according to the W3C (accepted standards despite what others may say) tables are to be used for tabular data. Layout should not even exist within (X)HTML (theoretically), it should all be semantic markup for the structure and content of a document. All design and layout should be handled by Cascading StyleSheets.

If you don't want to go with the 'standards', then your site will be less accessible to older, newer, text-based, and voice-read browsers. It's worth learning how to use CSS to style, and to write valid (and semantic) markup for your content. It will guarantee that your site will work with future standards compliant browsers, just as well as it works now. It's also a hell of a lot easier to update a site where the styling is in one (or a few) styelsheet(s). You just change the stylesheets and you have a whole new site with the same content.

Hope that was helpful.