I found this on support.microsoft, hope it helps.
P.S: I did not test it.
1.) Open Registry Editor
2.) Expand HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0
3.) Create a new Key under 12.0 called ServerLanguage
4.) Right-click ServerLanguage, select new String value and give it a name of 1033
Note: 1033 is valid for US English. To determine the appropriate language value for other languages, see the following web site: http://technet.microsoft.com/en-us/library/cc824907.aspx
5.) Close the Registry Editor
6.) Re-run the "SharePoint Products and Technologies Configuration Wizard"
The language is not supported on the server
The language is not supported on the server. 2