How the lights blink to the music

We are using a off the shelf product from Light-O-Rama, (also known as LOR).  A 16 channel control box is connected to a PC running Windows XP or Vista.  Music is manually sequenced on the PC to turn on / off, brighten / dim, flash, etc.. a given channel or multiple channels as the given song progresses.  Viewers can hear the music either via outdoor speakers or via a low powered FM transmitter.  Multiple control boxes can be chained together giving you 16, 32, and more unique lighting channels.