Thanks qhn. Someone has done this using another laptop but was able to swap the Atheros for an Intel 6230 using by doing the following:
DO THIS FIRST:
Download the drivers and utilities for BOTH of your wireless cards (Intel, Atheros, etc.) before proceeding.
Uninstall all the original drivers and utilities for your old card first.
Replace the old card with the new Intel card. Make sure you have enough antennas for antenna connectors (2x2, 3x3).
Then, install the new Intel drivers and utilities for bluetooth, wifi, & Widi. There will be an .exe or install for Widi, bt, and Wifi/My wifi.
Finally, you can finish by installing "Wireless Console 3" from Asus Support so that your keyboard wireless-shortcut works correctly using the fn button.
I am going to give this a go.