msiexec and appcompact issue

i have the following questions, if anyone can answer that would be helpful, i have googled and i am very confused after reading articles and user experiences.

problem: The MSI created using InstallShiled does not install on windows-7, if the user does not have admin privileges

1. do i have to install any shim for MSI developed with InstallShiled 11.0
2. do i have to install shim for for the msiexec executable.
3. does Microsoft provide these shims by default, if yes, how is this installed on client machines
4. what is the purpose of enabling the AppCompat engine ? if it is disabled does it mean that the shim will not be used?
5. Can i use ORCA tool to do something similar to the ForceAdminAccess hack in AppCompat Toolkit

appreciate your time and attention

thanks tom

This is not related to shims or AppCompat. An install does not break security rules just because it is an install. If the setup requires access to areas of the system that are not allowed to limited users then a limited user cannot do the install. A limited user cannot change restricted areas with an MSI any more than by running a program. Group Policy can be used to do the install with admin privilege on behalf of limited users using AD/GPO stuff, that's the exception.

I assume the setup writes to paces like HKLM or the ProgramFiles folder that limited users do not have write access to.