Sometimes you want to be able to access the contents of an MSI without having to install it. This is possible by running the Windows Installer MSIExec program with a few chosen parameters:
msiexec /a FilePathToMSI /qb TARGETDIR=TargetFolder
Where FilePathToMSI is the file path to the source MSI file, and TargetFolder is the path to extract the contents to.
More command line options can be found on MSDN here.