Is it really a good idea not to run as admin? (OK, bad phrasing--it's never a bad idea. I really mean: is it a bad idea to run as admin?) Running as normal user instead of admin was certainly a good idea on pre-Vista versions of Windows--if you were an admin, you could do anything anywhere and nothing would even try to stop you (or an executable silently running as you).

However, on OS X and newer versions of Windows, you are prompted for your password (or, on Windows, at least just confirmation if you're already an admin) whenever you do anything that requires admin privileges--e.g., modifying anything in the file system besides your profile folder, changing system-wide settings (like power management or the computer's hostname), and the like. You're prompted even if your account currently is an administrator. Even from Terminal (in OS X) you have to sudo for certain commands (and in Windows you'll have to do the equivalent right-click-and-choose "Run as Administrator," even if you are one, when you start the command prompt, to give it that extra level of elevation).

I don't really see how it's different, other that running as a non-admin makes you think of the username, as well.