One of the new features in the Autodesk product family "2013" is a new, alternative method of obtaining localized versions of products - using an additionally installed "Language Pack". By installing the selected language pack you get a fully localized product (the same as from the full installation), but you can also easily switch between languages, without having to install full, standalone language versions on your computer. The separate additional language pack takes only about 120MB of disk space above the original version (e.g. English). You can also add it to you network deployment.
The language of the CAD application can be specified in the runstring - in the launch icon of the product - so can have e.g. three AutoCAD 2013 versions on your desktop:
Language switching is performed with the parameter "/language" in the acad.exe executable (the appropriate icon is added automatically by the setup program of the respective language pack):
For AutoCAD 2013, these language packs are available for download: English (e.g. for your purchased localized version), German, French, Italian, Spanish, Brazilian Portuguese, Czech, Polish, Hungarian, Russian, Korean, Simplified Chinese, Traditional Chinese.
E.g. with the language option "de-DE" (and downloading the German Language Pack) you will make a German version from your AutoCAD:
Language Packs for the individual CAD applications can be freely downloaded from the product support pages of the respective product. Currently, the language packs are available for AutoCAD, AutoCAD LT, AutoCAD Mechanical, Architecture, MEP, Inventor and Inventor LT. Don't forget to fix the Content Service (IndexingServiceError.LocaleMismatch).