I've now solved this issue.
I was using the 8.xx drivers from Nvidia but after many, many attempts with drivers which resulted in no 3D, no video, freezing and even BSOD I finally found that the nVidia Detonator/FW Driver v23.11 driver is the one which works perfectly with Dark Omen full 3D mode normal resolution at 60Hz.
Now, onward to the dread king!