Two of those card you will be able to run 5 to 6 monitors with out any problems. Just read up on eyefinity it will help you and make sure you have a good PSU that can handle the two cards.
Make sure you get either a Corsair, Antec, Seasonic, XFX, Siver Stone, and some models of OCZ brands. To be on the safe side 850w and up. Good luck to you.http://support.amd.com/us/eyefinity/Pages/eyefinity-dongles.aspx