If you are going with quad SLI get the Dell 30 inch monitor. The Dell and Apple 30 inchers are the only ones that can take full advantage of the high resolutions that the quad setup is capable of (2560 X 1600).
thank you for ringing into this... I know you have a 7950 card and I forgot about the 'Hi-res" issue. The 7950 cards need a monitor that will support that resolution or the performance gains will not be seen.
that is another reason allot of people bad mouthed the card... no only were they running the card on a motherboard that did not 'fully' support it, they were clueless about the min resolution spec and were running the cards on a typical 1280x1024 setup.