I think I would speak to Asus before spending any money. Mini-PCI wireless adapters are available on e-bay etc but there may be something in the Asus BIOS which means they expect Asus branded adapters (even if they are actually made by Intel etc).
This sort of restriction has proved true of some HP models.
I was quite surprised when I managed to transfer an Intel unit from a trashed Philips laptop (found by the roadside as if thrown from a vehicle) into a Dell, without any prob.
The wires are probably antennas. I imagine it would work with only two of three connected.