Hi samrc,
If you need high levels of accuracy in the timing of the acquisition you'll need to use the trigger lines of your camera. Otherwise you would be relying on software timing and the latencies of the GigE interface which are not necessarily deterministic. The spec sheet for your XCG camera indicates that you can use pin 11 of the 12 pin connector to trigger the camera. You'll need to use a DAQ card or some kind of hardware that you can generate a digital pulse from to trigger the two cameras simultaneously. This topic is discussed in much more detail here by another NI employee. In terms of the LabVIEW programming, you'll also need the IMAQdx drivers, which are part of the Vision Acquisition Software package.
For your future reference, this type of question would be better suited to the Machine Vision forums, but feel free to respond here if you have any more questions.
