Joint beamforming microphone arrays and multi-channel acoustic echo cancellation (AEC) can be efficiently applied for hands-free speech communication. Especially, systems relying on adaptive generalized sidelobe canceller (GSC) structures are very promising, since they combine high noise-reduction performance with computational efficiency. So far, robustness of the GSC was very challenging, due to reverberation and non-stationarity of desired signals and interferers. In this contribution, we present for the first time a real-time system which integrates GSC and stereophonic AEC. It is robust against desired signal cancellation while highly suppressing interference and acoustic echoes. The realization on a low-cost PC platform, with the microphone array connected directly to the universal serial bus (USB), provides maximum hardware and software compatibility for personalized mobile computing devices and desktop PCs.