Yes, video cards won't do so much for Poser renders but the increase in overall system performance for the display is dependant on hardware. Regardless, display throughput performance increases with more video ram which is only available with today's sophisticated video cards. As far as VM and Poser goes, chances of using up to 4GB would be rare (you'd have to have one heck of a busy scene going on). It is better to up the VM and take the risk of a crash than to not up it and certainly risk crashes more often.