here the link again.

http://www.varranger.com/vforum/index.php/topic,878.0.html

If you have the 910, why do you need vArranger?
I don't say that there is no need, but I want to be sure that you will have a use of it.

For the PSR-S910, you only have to plug a USB cable to the PC.
It will be used as the master controller and the sound module.