Just about any AM3 board will work, but... What do you plan on doing with the PC? Do you need USB 3.0? eSATA? Firewire? Onboard video? SLI / CrossFire? Give us a lil more info...
You want at least an entry level 800 series mobo as 700 series would require a mandatory BIOS update for Thuban. State budget, use of rig, yada yada Btw do u happen to live near a Microcenter?