The general rule of thumb is to get the best video card you can afford, and a CPU fast enough not to hold back the video card.
Review and testing results of the Radeon HD 6650M suggests that it should do Medium graphics in the games you listed. But are you OK with that big 17" laptop? AMD Radeon HD 6650M review
Look this over: Acer Aspire AS5750G 15" Notebook $680
Core i5 2410M(2.30GHz) 4GB RAM 500GB HDD 5400rpm 15.6" 1366x768 LCD w/ NVIDIA GeForce GT 540MNVIDIA GeForce GT 540M review