Networking two pcs

Hey all,

My friend recently got a cable/dsl connection and he was trying to network two pcs…
I’m not asking how to connect two pcs using a crossover cable, rather my question is it possible that when two pcs are connected using a crossover cable and the “server” pc is turned off to use the net with the other pc? Btw, he is using pci ethernet/lan cards not inbuilt ones, if that makes a difference

I ask this because the guy who installed the cable for my friend seemed to imply this was possible…So my question is whether this is possible and if so how?

I must confess, I have no idea…

TIA…