>Style sheets can also be used to control layout (and are becoming increasingly important for doing so, as I understand it) but can be tricky to understand and implement.

It might also be worth noting that the asp.net templates supplied by MS for VS2005 are almost exlusively designed to use DIV elements and CSS. Learning to design your pages in that way will lead you to be able to implement Themes and Skins in the future.

http://msdn.microsoft.com/asp.net/reference/design/templates/

This link has some templates that show how asp.net 05 was meant to be used with style sheets.