They came out with a walk-behind machine and installed the wire. I just told them where I wanted it.
I think the wireless systems have come a long way. Unless you have a really large area to cover, I would look at the wireless systems.
Jaggirl made a good point: Our dog knows his boundaries very well. All we have to do now is put a the collar on our dog and he will stay a good 10 feet away from where he knows he will get a jolt. Even without the collar, he stays in the back yard. When we go for a walk, he waits until we pick him up and carry him across the "invisible line" that he knows he can't cross by himself.