Thanks gumpyMike.
So I can basically take the setup in the diagram I posted however instead of of taking the PWM output from the Arduino I take the output from the WS2801? with the WS2801 setup the same way I would power a single LED?
OR...
This setup from the datahseet where from what I can tell the only difference is the polarity reversed? In this schematic each channel from the WS2801 switches the transistor just like in the diagram I posted.
Just for my own knowledge, what does the "constant voltage with external switches" achieve? What does adding the op-amp do?