The problem with using tables:
- mixes presentational data in with your content.
- This makes the file sizes of your pages unnecessarily large, as users must download this presentational data for each page they visit.
- Bandwidth ain't free.
- This makes redesigns of existing sites and content extremely labor intensive (and expensive).
- It also makes it extremely hard (and expensive) to maintain visual consistency throughout a site.
- Table-based pages are also much less accessible to users with disabilities and viewers using cell phones and PDAs to access the Web.
Read it, Learn it, Do it.
Other thoughts: We really need a Web Design/Development forum with a link to this site on a sticky post, and where people can come for help to break bad layout habits.