Vista - Installation problem for non-admin users

Hello,

I guess I am facing an administrative privileges issue with Vista. I have a
custom application which is sent out to the users as an .msi file. I am not
able to install this .msi file on Vista for non – admin users.

I get the following error
Error 1303. The installer has insufficient privileges to access this
directory: <Folder Path>. The installation cannot continue.
Log on as an administrator or contact your system administrator.

Also the setup tries to add some dlls in system32 folder, and another follow
on error that I get is:
Error 1304: "Error writing to file [file name] verify that you have access
to that directory"

When I right click on the setup.msi, there is no option of “Run as
administrator�.

Any ideas on whatz going on? How do we let a non-admin user install the
setup on Windows Vista?