Aperture or Lightroom and why?

on a mac or unix system, no one runs as root and therfor a virus executable file does not have administrative  rights and wont execute, unlike windows where by default it is set up as user having full administrator account access, and any program can execute. windows at its core, is still based on the old windows nt framework and has lots of flaws that are easily exploited.

windows internet explorer uses active-x, which basically embeds an application inside the web browser, and executes as the system user, so you can actually go to a site that has a malicious active x control embedded in it and instantly get infected. on mac and unix systems, this doesn’t exist.