If someone is interested in the solution:
Use OpenOffice Spreadsheet to save the XLS as UTF-8-CSV. Then read the CSV with PHP and transform the strings with
[B]mb_convert_encoding($String, "UCS-2", "UTF-8");[/B]
from UTF-8 to UCS-2 and write them to the database.
Same thing the other way for reading and displaying:
[B]mb_convert_encoding($String, "UTF-8", "UCS-2");[/B]
Don't forget the HTML-Tag to define the content type:
[B]<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">[/B]
If you want to use the function mb_convert_encoding you have to enable the mbstring extension of PHP. For Windows just uncomment the php_mbstring.dll in the php.ini.
See the PHP reference for details: http://www.php.net/manual/en/ref.mbstring.php
Greetings,
Daniel