Take off the SLI bridge and it will work. Coming for personal experience. I have 2x 7600GT's, non-SLI and 3 Acer AL1916W's. It's a really wide desktop, not several screens with the same thing. To set it up you have to go to Display Properties under the Settings tab and change it around. This can't be done in SLI to my knowledge. With those cards you don't need SLI.
You can setup up to I think like 15 monitors per PC I think is the limit for Windows. It will probably drastically slow with all those monitors and having to use PCI GFX cards or something, but 4 monitors is more realistic and can be done with your cards.