Tables for Data
For nearly a decade, tables and layout were synonymous when concerned with web design. Only recently has the drive towards CSS positioning finally allowed tables to be relegated to the unfashionable pile. Don't forget, however, that tables had a clear purpose from the beginning: to present tabular data.
In case you forgot all the tags not used for layouts, such as thead and colgroup, this Advanced Tables Tutorial has all the info you need to properly structure your data.