This whole security policy/administrative priviledges thing is a point where Windows and OS X are everything but good examples. I'm not talking about vulnerabilities (perceived or real), but usability. OS X is built around the one desktop user case allowing this user pretty much everything. Windows nags the user with popups which noone understands what they mean or why they come and where everyone just hits OK anyway (of course slightly exagerated). They have not found a good solution either.