I third the Kimball suggestion. However, for a comprehensive book that covers everything about SSAS from the inside out I recommend "Microsof SQL Server 2005 Analysis Services" by Edward Melomed, Irina Gorbach, Alexander Berger, and Py Bateman.
SSAS is so involved that any one book is not going to cover everything you need to know, but this book will come the closest.
Reporting services was mentioned a couple times and I third that as well. However, if you are going to serve the cube in a cube browser you are probably going to need to consider Excel (preferably 2007) or performance point/sharepoint.
Reporting services has it's limitations with regards to drilling into the data. Further, Reporting Services is ill equiped to deal with KPI's, Data mining, What if analysis, and open dimensionality. Some of the best things you can do at this point is to get the business requirements as firm as possible.
P.S. If you were only going to use Reporting Services for the client front end why not just read off of a relational datamart?