"This guide is about LEDs (Light Emitting Diodes). It starts off with a little theory and then jumps into a section on how-to calculate resistance values for LED current limiting resistors. Next, I'll cover a simple circuit, which can be used to make a blue LED work with most any motherboard. The last part includes more pictures of LEDs in action."
FULL STORY @ SYSTEMCOOLING (http://www.systemcooling.com/modules.php?name=News&file=article&sid=409)