ArmA 2 is a first person shooting game (FPS) with single and multi-player modes. Its graphics rendering engine is particularly demanding and a handful for many machines. As the results are given in frames per second, high is best.
On our low-end machine, Windows XP is way out front. At our settings however, the game has trouble whatever the OS. You need to reduce settings to get a sufficiently fluid image.
Once again, Windows Seven seems better able to exploit the high-end components of the computer. It does better than both XP and Vista, with Vista down on the other two in this test.