Originally Posted by theducks
In W7 being in an administrator group is not the same as being an administrator in XP.
In XP you always ran (admin) elevated.
In W7 (Vista) you just have the right to elevate via UAC.
In Unix, you would SU (sudo in Linux) to elevate a task right. The difference was SU lasted until terminated.
I assume the OP is referring to the Run as administrator
I've highlighted in the attachment
Its an artefact of Windows Vista, Seven and Eight - and as far as I know its not needed for calibre, I have a recollection of KG posting that when it is used some calibre features wont work.
See Teach Your Apps To Play Nicely With Windows User Account Control
for a complete and very detailed explanation of the issues at hand (not for the faint hearted)