A very good article on SharePoint skinning….
Real World Branding with SharePoint Server 2007 Publishing Sites (Part 1 of 2) - http://msdn.microsoft.com/en-us/library/ee354191.aspx
Real World Branding with SharePoint Server 2007 Publishing Sites (Part 2 of 2) - http://msdn.microsoft.com/en-us/library/ee354190.aspx
