Administrations rights are needed to install language packs.
You can install additional language packs on your PC
You can see what languages are available by clicking on the "Choose a display language" drop-down.
Windows 8.1 -
Windows 7 - Region and Language, Keyboards and Languages tab
Windows XP -
You can change the language Windows uses to display text in dialog boxes and other items of the user interface
Language packs let multiple users who share a PC select different display languages.
Start > All Programs > Microsoft Office Tools > Microsoft Office Language Settings
Regional and Language Options, Languages tab
Select Case Application.LanguageSettings.LanguageID(msoLanguageIDUI)
Case msoLanguage.msoLanguageIDEnglishUK: Call MsgBox("English UK")