Have you looked at any of the new GeForce 4 cards?

Every GeForce4 chip has dual 350mhz RAMDACs, and as per NVidia's requirements, every card has to be dual head enabled.

Unfortunately, most of the companies making them are going the skimpy route, and putting 1 VGA or DVI out, and 1 TV out. I'm not sure how this qualifies as "Dual head", but whatever. Anyway, the good news is that some of the companies making GF4 cards are not skimping, and are actually putting dual DVI outs on the board, with an adapter to use VGA if needed. Take a look at some of the reviews out there, like this one and you should get a pretty good idea whether or not it will work for you.

I'm guessing that the top of the line GF4 will do what you want, and be much cheaper than the 3dlabs card.