If you want to run two Nvidia cards then you will need a SLI board (Nvidia chipset). If you want to run two ATI/AMD cards you will need a CrossfireX board.
Since it is an AMD processor I would recommend Crossfire as AMD's chipsets are great. but, if you already have an Nvidia card or have your heart set on one, then go with this one
Oh, and you aren't too terribly far away from me as I am NE of Chatt-town.