Which windows cd computer repairer/shop use to reinstall fresh copy of windows by using customers COA?
Any legal OS cd is just a copy of that OS and they are all the same. The reason the COA is on every retail computer is for re-installation purposes, and is actually a different number than the machine code used at the manufacture. Microsoft knows what COA’s are registered to what machine codes and unless you change a major piece of hardware (motherboard, harddrive) it will always re-authorize no matter how many re-installs of the OS you do.