Usually it is possible to use your favorite compression utility to treat a Microsoft Installer Package (MSI) like it is a normal archive. Though, sometimes this does not work. In this case one can use the Windows Installer Tool (msiexec.exe) to extract the files from the MSI package. The tool can open a MSI package in “Administrator” installation mode, where it can extract the files without performing the install.
This command runs the setup giving the ablility to extract the files without actually installing the application:
Msiexec /a mypackage.msi
This command extracts the files to the specified location without user interaction:
msiexec /a mypackage.msi /qb TARGETDIR="C:\MyFolder"
Please note this can also be useful in case an MSI package has been configured to block install, which is used on certain versions of Microsoft Windows.
More Info MS KB Q227091
Found on: http://smallvoid.com/article/windows-extract-msi.html