That board has a max sample rate of 250 ks/s for a single channel so depending on how many channels you need to capture, the .3 msec should not be a problem. The display of data depends on several things and also on your definition of real-time. For example, if you set a sample rate of 1000 s/s and request 1000 samples to be transfered, your graph/chart will update once a second and display the entire 1 second's worth of data. If you request 500 samples, then the graph/chart will update every .5 second but you will only have half of the data. I don't think it makes much sense to try to update the screen more than a couple times a second but that will be up to you when you write the program.
