Just so you understand what's happening, and why it's important:

Twisted pair cable is designed so that interference is self-canceling on the cable. This is accomplished by the twists in the cable. Since Ethernet only uses 4 out of the 8 wires, you only need 2 pairs. Forthermore, it was designed by someone in the military, so the design is a little f'ed up. instead of using pins 1,2,3,4 like a normal human being, they decided to go with 1,2,3,6 leaving 4 and 5 in between the active pins. Basically, you rather pointed to (what I believe is) the problem with your earlier post. If you use the wrong pairs, two of your wires are no longer twisted, and therefore, no longer shielded at all, so you have 2 100' antenna's on each of your network cards. Since you live in a high emf area (Enough to kill wireless) This would be exceedingly important to your setup.

Let us know how it turns out, I'm curious now.