Finally got it to work!
My mistake was that I plugged my gaming reciever into all the different USB-slots I have. That created two "unknown devices" in my task manager and I first only installed the driver
into one of them(USB-slot 002# and 003#). But at that moment I had the reciever plugged into USB-slot 001# which is connected to the other "unknown device" in the task manager (USB-slot 001# and 004#).
So I just installed the "Xbox 360 Wireless Receiver for Windows Version: 18.104.22.1689 [8/13/2009" driver into that one also ^^. I'm too lazy to switch the reciever into another slot you know..
Hope this could help some and thanks everyone helping in this thread!