I'm going to be building a new computer and need help with choosing a motherboard, cpu, and gpu.

Budget: Instead of having a specific budget, I'd like to keep it as cheap as possible while meeting performance requirements. I multibox 5 accounts, and I'm looking for a new combo that can run them. I'd like the main window to get 60 fps on at least good settings, and the 4 others to be throttled at 20 fps. I'm only going to use 2 monitors, and I typically prefer AMD/ATI to Intel/Nvidia. I'll be using 16gb of ram, and would like something that has room to be upgraded at a future time.

I'm planning on going with a 750 watt power supply, and just a regular HD instead of a SSD to keep costs down to start. I am, however, open to suggestions for the rest of the build.

If I forgot anything, feel free to ask. Thanks for the help