I guess you are referring to this:
http://www.youtube.com/watch?v=pQYIbLgtcuU

I also have vArranger using my laptop and SD2 which I use at Nursing homes. A great light setup. I use an M-Audio Uno. The midi out goes to the controller keyboard, the midi in to the SD2(SD4), and the USB goes into the laptop. This is because you are controlling a program in the laptop.

However, you do not need a laptop to simply use the SD4 sounds through the keyboard. You midi both together and set up KN7000 as the master and SD4 as the slave.

Bernie
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pa4X 76 ,SX900, Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact