Installer Detection has nothing to do with SpyWare
Installer Detection is primarily designed for backwards compatibility, it's purpose is to scan the name and resources of an EXE to determine whether an application is "likely" to be an installer program. If Vista thinks it is an installer then it is assumed that admin privileges will be required and the user is prompted to run the program with the required privileges.
An executable is assumed to be an installer if the executable name or description contains the strings "install" or "setup".
Installation programs designed for Vista use Manifest files to let Windows know that they require admin privileges, pre Vista installations won't contain this information. Without Installer Detection old installation programs would never have admin privileges and would always fail.
User Access Control (UAC) ensures programs do not have admin privileges by default which does help prevent SpyWare but Installer Detection has nothing to do with SpyWare prevention.
Biting the hand that feeds IT
