GCA-06 
http://www.imagesco.com/geiger/img/gca-06W.jpgShould I set it on Imperial  or  Metric
Countable Pulse Resolution & Range 1 Count Per Minute (CPM) - 5000 Counts Per Second (CPS)
Radiation Resolution: (Imperial).05 mR/hr
Radiation Range: (Imperial) Background Radiation* 18-22 uR/hr - 1000 mR/hr
Radiation Resolution: (Metric).0005 mSv/hr
Radiation Range: (Metric) Background Radiation* 0.18-0.22 uSv/hr - 10.0 mSv/hr
When I set it on Metric my readings are pretty close to NETC.
I just want to know what I am doing and I appreciate your help. Define CPM please in lamans talk 
because when I checked it on line ????Math was not my strong point.
as far as calibrating ?  basically it gives me these two choices
mSv/hr  or mR/hr   and 1 sec 1 Min or 5 Min
when I had it set to
mR / hr    and 1 Min  my readings were close to NETC'S 
I have an IMac so when I tried to download  the program  the NETC offers so I can be a "Beacon " here on Maui  it wouldn't take.
sorry for the bother 
I really tried to get all my questions answered on line  and when I was answered it was all Chinese to me DUH me!
and if I am bothering you sorry forget that I even wrote !
Love & Light