". . . these days most switches and routers support MDIX so it doesn't matter anyway which one you use"
Mark is referring to auto-MDI/MDIX, and he's completely right, if it's enabled, the cable shouldn't matter.
Also on some hubs/switches, two port jacks might be the same port, but wired differently (you connect to one or the other, not both), or there might be a way to change the pin wiring for an "uplink" port, or the "uplink" port might be wired differently from the other edge ports.
"use crossover cables for like to like devices and straight through for the rest "
Mark is also spot on like devices, but for the rest you need to know whether their NIC is wired MDI or MDIX. Basically MDI<xover>MDI or MDIX<xover>MDIX or MDI<straight>MDIX.
"host", "server" and "router" should all be "like" devices. "hub" (or switch) would be different.
