For those of you waiting for the new "Inside SQL Server" book, it is actually out now. Kalen decided to give it a name change, and the actual title is "SQL Server 2008 Internals". I've written a chapter on how the Query Optimizer works. It is currently #1 in the 3 related database/sql server categories on Amazon, so I'll say "thank you" to those who have already ordered a copy ;). Like my blog postings, there are a lot of sample scripts you can try so that you can "see" what the optimizer is doing - I find this technique to be a very good way to learn what is happening, and I hope it works for you.