Tutorial: How To Build A Computer

How To Build A Computer - Wikibooks

Building your own computer from individual parts not only saves you cash, but helps teach you the basics about computers that at least one person in every household should know.

Topics:
1 Choosing the parts
2 Building the physical computer
3 Choosing and installing the computer's software
4 Optimizing and Overclocking

So tell your kid to quit playing outside and build you a new computer :)