Nvidia Quadro NVS 280 AGP will do 1600x1200 in DVI, but you'd need a 280 AGP and 280 PCI to run 4 monitors.
They are dual and I want to be able to run 8 screen . Here is a link I found comparing multimonitor cards: http://www.multiplemonitors.org/Pages - Hardware/Hardware - Multi head Video cards.html Take a look