I've written a number of 24 Hours books for Sams (including Teach Yourself Visual Basic 2005 in 24 Hours and Teach Yourself C# 2005 in 24 Hours), and I agree that none of these titles will make you an expert in 24 hours - or even get you close. The goal of these books is to provide adequate, useful, and hopefully entertaining instruction for you to learn the basics of a language and its tools and allow you to begin creating your own applications using the language; yu won't know all the answers as you stumble along with your own applications, but hopefully you will have learned enough of the basics to understand what's going on and how to find help or experiment to solve your own problems. These books serve a purpose, but I don't think anyone (publishers, authors, or readers) really believe that the books will make you an expert in the stated amount of time.
james commercial developer, author, speaker, dude. www.jamesfoxall.com