Can I use four monitors with a dual-link dual-DVI card?
No, Dual-Link DVI works the opposite way around. It is used to send more data across a single DVI cable. This is used for monitors with very large resolutions (such as 30" monitors with a resolution of 2560x1600) as normal (single link) DVI doesn't have a high enough bandwidth to support a resolution that high.
The maximum number of monitors you will be able to use with that card is three, two for the two DVI ports and one in the mini HDMI.