The first display is intergrated. He's probably not using it, as the system disables the onboard GPU with a PEG card in there.
I'd say the CPU. Most systems nowdays runs dual-core. But the board might refrain you from getting a quad core. So, let me give out my suggestion:
Board: GIGABYTE GA-MA790GP-DS4H AM2+/AM2 AMD 790GX HDMI ATX AMD
CPU: AMD Phenom 9650 2.3GHz 4 x 512KB L2 Cache 2MB L3 Cache Socket AM2+ 95W
Total of all items included WITHOUT
taxes and shipping is set to: $309