I have never had problems with NVidia and Poser but I can't say the same with AMD and Poser Pro 2012 (which I have now).  Poser Pro 2012 and my AMD has OpenGL issues where I have to switch back and forth between the Preview and Render tabs in order to deal with screen freezes where it seems like it's not refreshing.  I don't have this same problem in Poser Pro 2010 with OpenGL nor do I have it in Poser Pro 2012 when I don't use OpenGL.

It's a pain but not so much that I'm going to throw away the software.  The only thing that upsets me is that Poser Pro 2012 was expensive for me to have this type of problems.  All of my heavy graphics work well with the AMD that I have so I just update the graphics driver hoping that one day either Smith Micro or AMD updates will solve my problem.

If I had a choice (money) to buy one then I would get a highend Nvidia card, not so much for Poser, but because I never had any troubles with Nvidia.