I am sorry for such a basic question, but I am still getting mixed signals:

Between like devices: use crossover

Between different devices: use straight through

Hub is like a switch and router is like a PC for this purpose

That makes switch-switch using crossover and switch-router using straight through... Does that make sense? Am I missing something, does anybody disagree and why? (I am sure in reality, wrong cables will work too, but for the purpose of certification....)