It's a tool from windowsphonehacker to help you to update your Windows Phone device to Wp7.8 easily. You just download the tool and install on your PC, and select language, then download language package and relevant documents.

downlaod: http://windowsphonehacker.com/files/seveneighter.zip

Another Update Method: http://www.wpxap.com/thread-550903-1-1.html

http://www.wpxap.com/thread-549404-1-1.html

source from windowsphonehacker