Fenix,
There are about 4 or 5 active threads on this very topic. I myself have a Hercules Prophet II 64mb that I just got as well, and I agree that the ghosting is absolutely horrible at all resolutions, especially when you're running an 85hz refresh.
Argh... people suggested new BNC cables (which I went and bought, cost me $55), people suggested that the monitor was bad, etc, but that wasn't it.
I think the nVidia chip is just very poorly made.