I wrote this post almost 2 years ago showing how to use CSS Adapters to control the rendering of server controls that output non compliant HTML (table based ones in particular). I’ve still been getting lots of hits and questions on the post but if you’re using ASP.NET 4.0 there is a way easier approach.

Read about LayoutTemplates here,

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.wizard.layouttemplate.aspx

Cheers