I believe that the Acer Aspire AS7750G with the Mobility Radeon HD 6650 is better suited for games than the SAMSUNG RF711 with a nVidia GT 540M. Had it been a nVidia GT 550M, then performance would have been more or less equal.
However, the Acer is heavier so if you are going to carry it around then that's something you need to consider as well.
However, you must take those ranking with a grain of salt. Benchmarking laptop video card performance is not as easy as benchmarking desktop video cards. Benchmarking desktop video cards is easy because all you need to do is build a computer, then swap in/out different video cards to do the test. The only thing that changes would be the video card and the drivers (AMD / nVidia) so it is pretty much cut and dry if you are trying to determine if AMD Radeon HD 6950 is better or worse than a nVidia GTX 560.
Laptop video card performance is tricky 'cause you cannot simply have a single laptop and swap in and out various different cards. You may be testing a Mobility Radeon HD 6650 in a notebook with an AMD Phenom II dual core CPU vs. a nvidia GT 540M in a laptop with an Intel Core i5 dual core CPU.