language settings in CRM 2007

Hi experts,

i am almost new to CRM 2007 and have the requirement ot change the default language to german.

When starting the web client, the log on site starts in english and in the dropdown select box there is only the langauge english to choose.

The sap user settings and also the browser settings are already switched to german, without any success.

Could anyone give me a hint, what to do, to make the application start in german?

Thanks in advance!

Kind regards

Andreas