You can use all NI-FrameGrabber with the same driver (NI-Imaq). One advantage is you can change the grabber without any changes in the programm. Another is, you will get an easy to use API and a lot of examples.
LabVIEW is a development environment. So, it is possible to call dlls like in other development environments. If you would like to use a non NI-Grabber you can call the dll of your image acquisition hardware. The dll and the necessary documentation should shipped with your hardware.
