I would suggest you get a copy of SQL Server 2008 Internals
by Delaney, Randal, Tripp and more. Excellent book on the internal workings of SQL Server.
http://www.amazon.com/Microsoft-SQL-Server-2008-Internals/dp/0735626243/ref=sr_1_1?s=books&ie=UTF8&qid=1289565465&sr=1-1