My friend Koroush Ghazi from tweakguides.com just finished the new tweaking companion for windows 8. It covers all of the features of Windows 8, including how to safely optimize and customize most of them. The book is equally handy for new users of Windows 8, as well as those considering upgrading to it. As before, it is available in a free Regular Edition and the paid Deluxe Edition.

There are also guides for XP, Vista and Win7, check it out here: http://www.tweakguides.com/TGTC.html

Quote :

The TweakGuides Tweaking Companion (TGTC) is the complete system customization and optimization guide for all Windows users. Designed for novice and advanced users alike, it is written in plain English to help you genuinely understand all key aspects of Windows and your PC. The guide covers every major topic, from the correct installation of critical drivers and software, through to simple explanations and recommendations for every significant Windows setting and feature, all the major performance and convenience tweaks and customizations, as well as detailed troubleshooting advice. Also provided are links and instructions for a large number of reliable free applications that can enhance your system and give you viable alternatives to purchasing commercial software.