When asked to create a multilingual image for your company or organization, you may be tempted to start with your existing image and add Language Packs.  This method can cause you problems down the road.

As a best practice, you should start with the Vista image as shipped and all of the Language Packs you intend to include before adding any hotfixes or applications.  Keep in mind the OS and the Language Pack need to be the same Service Pack Level. A Vista SP 2 image needs an SP 2 Language Pack for example.

Why is this important?

For hotfixes:

Although the many security hotfixes do not contain language dependent parts, some hotfixes do.  For hotfixes with language dependant parts, only the files for the languages currently installed will be copied to your system.  You certainly won't want files for 100 (give or take) languages installed to your system (if you are not using 100 languages). So for example if you add French to your existing image with hotfixes, the French files from these fixes will not be in Windows image.  While your next trip to Microsoft Update can resolve this problem, there are cases where you will break your Windows installation due to missing files.

For example:

If you add KB 940157 (Windows Search 4.0) before you add Language Packs your system will be missing key system files. In some cases your Windows Start menu will not function.

Also note that for applications that have Multilingual support, you neeed to install the application after you have installed additional languages..