Control of 32 DC motors

I'm building some sort of musical instrument using 32 small (12-24V) and cheap DC motors (no servos!) which need to be controlled (on/off and speed) by a computer. Can anybody get me to a place where I could find a solution for that or give me some hints on how to get that done? It would be great if it could be something similar to the lynxmotion SSC-32U USB Servo Controller (http://www.lynxmotion.com/p-1032-ssc-32u-usb-servo-controller.aspx), except that it should not be used for driving servos, but control the rotation speed of the motor. I've read in the web that pwm can get used to control speed of DC motors but I doubt that a DC motor can get connected directly to this board.

Also it is possible to
Also it is possible to modify a hobby servo for continuous rotation. How much speed and torque do you need for this instrument?

How much control of the motors do you need? Will they only be going a single direction, or forward and backward?

The less control you need, the easier and cheaper it will be to build the controller.