Working as limited user and creating seperate limited user account for Bitcoin is nice idea. Will help if running as limited user and executing wallet stealing program, if the stealer does not contain keylogger to get creditentials for the second Bitcoin account. Not even necessary to mess with NTFS permissions, because by default it is set properly on %APPDATA% folder where Bitcoin data resides. But it all comes down to this: Most Windows software must be installed or upgraded from administrative account. From time to time you also must run cracks for the software you install. If some crackpot binded crack with malware, and you run it as admin, your coins are gone.