Did you buy a Vista laptop from abroad and want it to talk to you in your mother language?
Try Vistalizator- this tool allows you to change display language in Vista editions other than (officially supported) Ultimate, like Starter, Home Basic, Home Premium and Business.
Vistalizatoroverrides the limit of one language on non-Ultimate Vista editions.
See details about using multiple languages in Vista. Portable.Vistalizator 1.40

Features
* Change Vista display language in less than 5 minutes!
* Uses official Microsoft Vista language packs
* You can install all 35 languages and switch between them easily
* Works in 32-bit and 64-bit Vista
* Compatible with Vista Service Pack 1
* User Account Control (UAC) compliant - prompts for administrative privileges
* Safe use - no file is overwritten/changed during language installation
(except for language upgrade after installing Vista SP1)
* Vista Speech Recognition works with all supported languages:
Chinese, English, French, German, Japanese,Turkish and Spanish
(go to Control Panel -> Ease of Access -> Speech Recognition Options)

Issues
Windows Update is sometimes not working. Anyway, there is a workaround:

* Run Vistalizator - revert to the original Vista language
* Use Windows Update, restart system if requested
* Change back your desired display language

It sounds annoying, but Microsoft usually releases patches once a month.

Windows Search 4.0 nowadays is automatically installed via Windows Update on Vista SP1.
This update of the integrated search engine in Vista is causing a few troubles:

* Some Control Panel items fail to open
* When you right-click the desktop and try to select Personalize, it fails to open
* There is some missing information and blank column headers in Windows Explorer

Simply uninstall Windows Search 4.0 in Control Panel -> Programs -> View installed updates.
Requires system restart, but there is no need to reinstall any new language.