I'm also having issues with dual display on my Nvida card.

GEForce 5700 Ultra - One VGA, one DVI

Monitor#1: Syncmaster 955DF 19" CRT, via VGA cable to VGA port
Monitor#2: ViewSonic A98f 19" CRT, via VGA cable to DVI/VGA adapter to DVI port

Tried Natit, Natit Dual 0.1 and Natit Dual 0.2

1) When booting, the POST screen and the initial apple grey screen come up on both. I know this is just the default mode of the card, as when in the BIOS it's on both screens mirrored.
2) Screen goes black (like normal when it's activating monitors)
3a) With both plugged in (even switching them around), only the monitor connected to the VGA port activates. Other stays black and goes to sleep.
3b) With only the DVI port plugged in (via DVI/VGA adapter) it activates it fine.
3c) With only the VGA port plugged in (directly) it activates fine.

So, when I have both plugged in, it appears to not be able to activate the DVI port on my card.

Any ideas?

Thanks.