
In the video without the PhysX card the screen doesn't shake and a nearby soldier is unaffected by the blast. In the video with the PhysX card the screen shakes relatively violently and the soldier dies (although he's slightly closer to the blast). Of course its possible that the second video could have been tweaked to further differentiate the two machines' explosions, but if simple effects like a screen shake requires $250-300 worth of hardware it's not hard to envision a lot of pissed off gamers.
[Update: fixed grammar error (moved over an apostrophe, added an "s")]
