Applications that Shouldn't be Repackaged

Existing MSI packages should be deployed as they are. If customization is necessary, a Transform (MST) file should be used to introduce that customization. If you repackage an application and find that it references the MSI.DLL file, it is better not to repackage the application. Microsoft Office 2000 and XP are good examples. These applications are hard coded to use the Windows Installer service, and may make calls back to certain locations within the original MSI package.

Applications containing system files managed by the Windows File Protection features of Windows 2000 and later are also to be avoided, such as Internet Explorer, Windows Service Packs and certain hot fixes. For these, a provided MSI or command line installation is your best bet.

Repackaging certain types of applications is not recommended. These include:

1. MSI files. Installations that are already in .MSI format should not be repackaged, but instead should be customized using a "transform." A transform customizes an .MSI installation without recreating it from scratch.
2. Transforms are applied at install time and are used to change the default behavior of the installation. The original .MSI file is needed in order to create a transform.
3. Operating systems. Capturing is not appropriate for operating systems or service patches.
4. Windows Media Player, Microsoft Internet Explorer, anti-virus software, and device drivers. All four types of applications listed make low-level changes to the operating system involving Windows File Protection.

Why don't we usually repackage an MSI?

First of all, MSI installations are already in a in a distributable format, so there is no benefit to recreating the setup. MSI packages are full of internal references, which cannot be captured and recreated. These internal references are critical to the self-healing functionality of MSI packages and are fundamental to their operation. Repackaging an MSI may result in uninstall problems and other Windows Installer related problems.

Finally, and perhaps most important, when the vendor releases and update or patch (MSP) for the product, it will be designed to update their MSI and not yours. When repackaging, all of the globally unique identifiers (GUIDs) used to identify items in the package are regenerated and will not match up to the updates provided by the software vendor package. There are no changes that cannot be implemented at install-time using an MST (transform) file. Aside from dictating installation preferences, you can add, delete or change any items you wish.