well i checked all PCs in that thread
I found one with a GTX 460 and i3 2100 which is sandy bridge? it got 25 fps in viewport.
And the other one thats a i5 2300 sandy bridge but with super good AMD card HD 7890 or something with 60 FPS
Suggests to me I could definitely get away with my current pentium G if I keep things simple and I can get away later on with a fast i3 and new GPU. The AMD in all tests was far better bang for the buck than intel. Example the 6 core AMD was faster than the i3.