Minor correction if you do talk to them, Cat 5 refers to the specifications the cable and plugs are made to, cross over refers to how the wires are connected to the plugs.

Cross over is the opposite of straignt through, both can be cat 5 cables.

If you hold the plugs side by side and look at the wire colors, in a cross over cable two of the pairs are reversed, in a straight through one the colors of the wires will be in the same place in both plugs.