Possible conflicts between USB adaptor and installed wireless device

I'll try and keep this simple as I can.
Bought Acer Aspire One, which comes ready to go on wireless with an Atheros card.
I wish to experiment with various home brew WIFI directional antennas, BUT antenna
is built right into this Netbook. Possible solution is USB wireless adaptor allowing the use
of various external antennas. Should I disable the Atheros device before installing files
for the USB wireless adaptor? Could this be a disaster waiting to happen? Do you
think System Restore can get me out of most problems? AND THEN there is the question
of also adding programs like NetStumbler and others which can give signal strength reports
and other interesting information about received signals. Is there a certain order to go about
when atempting to install these items? Perhaps this is to much for a novice to undertake,
but maybe with some help I can get it all to come together. I have spent hours searching
for answers to these questions to no avail.
Thanks
mike