You just need a Dual-Link DVI graphics card like the Radeon 9600 PC & Mac Edition. Such a card is old and slow, has passed the end of its product life, but in all honest I don't know jack about current GPU offerings for Windows. My Mac Pro includes a NVIDIA 8800GT to drive the 30" Cinema but I ignore if the same applies under Windows world. Other members'll provide a better, more specific advice.
Please note: having two DVI ports does not necessarily mean a graphics card is Dual-Link DVI capable.