I think the best way to go with such a setup is to go with a AMD graphic card that support eyefinity 6 (meaning supporting 6 screens). Readthis threadhttp://www.tomshardware.com/reviews/toxic-hd-7970-eyefinity-6gb,3264-9.html
You will need as mnimum the HD 7870 card but I would recommend the 7970 to be sure you can run all screens in that resolution. You may even need a to have to do a two-cards setup but since it's not for gaming or that sort of stuff I'm not sure. I would google around for earching a bit more about the eyefinity 6 option.