Tom's Hardware Guide published the first part of their PC building guide. In this edition they focus on selecting the right components for your rig:
Before any parts are selected, a builder should clearly understand the machine's intended function. General purpose systems that deal with such tasks as 2D games, Internet browsing and document creation, will obviously have modest hardware requirements. In contrast, high-end 3D gaming systems will require better graphics, better cooling and a larger power supply. Special applications, such as 3D model creation and home theater PC use, should also be considered - these tasks require specialized hardware.