Most administrators know that users should log on to their computers using accounts that are members of the Users group, but not the Administrators group. By limiting your user account's privileges, you also limit the privileges of any applications that you start—including software installed without full consent. Therefore, if you can't add a startup application, neither can a malicious process that you accidentally start.
With versions of Windows prior to Windows Vista, however, not being a member of the Administrators group could be very difficult, for a few reasons:
Many applications would run only with administrative privileges.
Running applications with elevated privileges required users to either right-click the icon and ...