The CSL PCIe wireless card I have now full reception and the problems have finally vanished into thin air.
The drivers from the CD can also be installed easily and it is not proprietary software installed, as eg. The AVM Stick was the case.
I am so far as fully satisfied and can the CSL Card with normal standard antennas (disturbing to a mid tower not) for Win7 64bit users and owners of a 54Mbit / s Fritzbox friend.