Reading through the reviews on the monitor you were looking at, it does appear to work for AMD, which must mean it's HDMI 1.4a compliant. However, it doesn't support true 120hz. I do know that HDMI is only able to do 60hz, but with HDMI 1.4a it does double images at 60hz at 720p resolution.
There is nothing wrong with using Nvidia on an AMD system. The 3D vision is a lot better than AMD's HD3D. I purchased a monitor that has both so I could be able to do either. After using AMD's for a day or 2, I then tried Nvidia's 3D vision. It's a lot better. 1080p and easier/better to use software Vs. 720p max res and 3rd party software you have to also purchase, which is not as good.