This is a tool I have written to examine the box it is run on for MSI products which are installed per-user.
This looks at undocumented registry entries as there is no documented interface to obtain the required information.
This tool would mainly be useful in a controlled environment where products are automatically deployed and these products would be expected to be installed per-machine. Per-user installs in such an environment will cause problems and would be typically caused by support staff double clicking on MSI files (which don't force a per-machine install).
This command requires no parameters and can be used via CSCRIPT or WSCRIPT.
If user names are being reported as SIDs then the "SidToName.exe" program was probably not found in the same directory as the script. This free program can be downloaded from "http://www.joeware.net/".
See the "Registry Usage" section for other useful information.