Bij die link van ohooghuis (bedankt voor de tip, btw

) staat het volgende:
3D
Here's where this system really shines, 3D speed and quality is excellent on all monitors. The GeForce3 is simply amazing, and the GeForce2 MX cards are very powerful as well.
A disappointment was the multi-monitor OpenGL support: as with most cards on Windows 2000, you can run OpenGL applications on the primary monitor without disabling secondary monitors. But in addition to this, Nvidia is one of the few manufacturers who supports OpenGL acceleration on secondary monitors as well. Unfortunately, this feature doesn't work with the GeForce3, even though the Nvidia documentation states that you can mix different chipsets.
If I enabled the 'Advanced Multiple Monitors' option, all OpenGL applications simply crashed during startup. I then used one of the GeForce2 MX cards as primary and disabled the GeForce3, and everything worked fine: OpenGL apps were fully accelerated on both GeForce2 MX cards, and windows could be moved from monitor to monitor without problems. The only limitation is that windows can't stretch across multiple monitors.
So if you need OpenGL on multiple monitors, you should stick to GeForce2 MX cards. TNT/TNT2 combinations also work fine, but are a lot slower.