As discussed in the FAQ, to run the Dell 3007 at full resolution your video card needs to have Dual-Link DVI.
Basically, in a normal DVI plug, half the pins are not active. Thus, you can't send enough data down the cable to tell all the different pixels what to do.
The page that you linked to doesn't seem to make any mention of having Dual-Link DVI, so you need to look a little further.
Accoring to the manufacturer's page at
http://www.nvidia.com/page/8800_tech_specs.html both of the plugs
are dual-link DVI capable, and are suitable for "Two dual-link DVI outputs for digital flat panel display resolutions up to 2560x1600"
A common misunderstanding is to not realise the difference between Dual DVI outputs (ie, two plugs) and Dual-Link DVI (ie, ability to run very high resolution displays)