If you have Windows 7 Home Basic, Home Premium or Business, or if you have the Windows 7 Starter edition you cannot install a Language Pack, also known as a MUI or Client Language Pack, as explained in the first article of this series. However, any Windows 7 edition permits the installation of one or more Language Interface Packs (LIPs), which have only the most commonly used parts of the Windows 7 GUI translated, yet are limited to non-major languages.
Which Localization of Windows 7 do I have?
Before you set off to install a LIP in a given language make sure your Windows 7 computer has the prerequisite parent or base language installed, as explained in Bright Hub’s article Understanding Windows 7 Language Packs: Introduction and Architecture. To find out which localization of Windows 7 you have, go to Start Search and type msinfo32. In the right pane of System Information / System Summary check the value of the item Locale.
List of Windows 7 LIPs with the supported base and parent languages in brackets:
Azeri (en-US, ru-RU)
Basque (es-ES, fr-FR)
Bosnian (en-US, hr-HR, sr-Latn-SP)
Catalan (es-ES, fr-FR)
Kazakh (ru-RU, en-US)
Luxembourgish (fr-FR, en-US)
Serbian (sr-Latn-CS, en-US)
Sesotho, Setswana (en-US)
Uzbek (en-US, ru-RU)
They can be obtained from Microsoft: http://windows.microsoft.com/en-US/windows/downloads/languages
If the display language you want to install is not listed here then it is not available as a Windows 7 Language Interface Pack, but most likely is available as a Windows 7 Language Pack. More Information about Windows 7 Language Packs can be found in
Understanding Windows 7 Language Packs: Introduction and Architecture: http://www.brighthub.com/computing/windows-platform/articles/56625.aspx
Windows 7 Language Packs Details and Availability: http://www.brighthub.com/computing/windows-platform/articles/56630.aspx
as well as the first part of this series: How to install a Windows 7 Language Pack.