We have a target we want to achieve for minimum spec:
2 core CPU 2GHz, RAM 4Gb, DX11 GPU (any)
We are not there yet with GPU (current GPU needs to be at least nVidia 650 or AMD 6700 - roughly), however, CPU and RAM are now fine.

Internet will need 5MBit download and 1MBit upload speed. (that should be relatively low-end broadband)