Hi everyone. To change the language you have to download the english client.

First of all you have to visit eu.battle.net. Then log in and choose account to reach the link "Download Gameclients" or something like that. (In my case it was in german) And then choose your wanted language for the Starcraftclient.

I would suggest that you deaktivate the Peer-to-Peer
download. My notebook downloaded at 200-300kb/s while Peer-to-Peer was aktivated and with out Peer-to-Peer it was at 800-900kb/s