Since Prepar3D v2 requires DirectX 11 to run at all, this could be the main limiting factor when looking at P3D.
This poll is really just to figure out what percentage of members actually have a Graphics card (GPU) which supports DirectX 11, but it does go a bit further.
I had hoped to include a chart of DX11-capable GPUs, for those who don't know what they have, but since I couldn't find a nice chart which covers both Nvidia and ATI/AMD, if you don't know, just ask here and no doubt someone will help you.