Horsecrazy, go to youtube and see how fencing is done there. My corners use 5 posts, 3 form an L, the other two run parallel to the ground, with notches cut in the uprights, then wire forms an X and are twisted as tight as possible and then some. Those line posts you have are fine. To prevent the wire going down, every three or four posts tie the wire at the insulator with plastic bale twine. Put a fence staple on the back of the post. Should the insulator break the twine will hold the wire up. Wire is the best to stay with, any fencing pro will tell you that. The others are for fencing inside the perimeter fencing.