ADministrator is an ADMINISTRATOR!!!!, its for administrating jobs only!!!
If your system is correctly installed no one has the rights to access files/dirs owned! by the admisnistrator.
For the case you installed your system Adminstrator only you will drive within a bunch of problems when using the internet.
So I hope, you created at least one "stupid" user account..
C:\Program Files (x86)
Arduino Download stuiff like json e.t.c.:
since Arduino v1.5 its called Arduino15
Additional hardware & libraries:
Its alo possible to install additional stuff system wide with help of the administrator account within the Arduino system.
But they are lost on any update respectivly every update is much more complicated.
YOu will also loose the advantange of the "user system" with diversitied library installations.