MSI log files can be incredibly useful for creating silent installations of vendor provided MSI's - for example, an application that has a serial number, or asks various questions, if you do a manual install fully logged (msiexec.exe /i /L*v c:\temp\funkylog.log) and then look in the log for the command line - it will change as the installation progresses but often things that the installation asks the user for are uses as properties, which can be entered in the command line, or in an MST and aid a silent installation.