NIquist

This should be no problem. The sound input VIs all work with stereo and provide two waveforms out. Look at the Finite Sound Input.vi example to get you started. Of course, whether or not the data will be truly simultaneous depends on your audio card. I would think that most of them use 2 ADCs but I can't say for sure.

You say you have a particular galvo (6215H) but don't mention the model of the servo driver board. That is what will determine how you connect to the PC. Most servos are analog IN which means you'll need some type of data acquisition card in your PC to control it. Once a servo is tuned to its galvo/mirror you can just send the system a command signal which will move the mirror in a controlled way. What type of command you send (+/-3V, +/-10V, etc.) again depends on the model of the servo board. If it's a CTI servo then it will be +/-10 Volts).