In the following minimum-detail benchmarks, we turned every setting down as low as it'd go except for texture quality, which we left at high.
The only card that struggles at 1280x1024 is the GeForce 210 DDR3. AMD's Radeon HD 6450 manages to keep its minimum frame rate above 30. All of the other cards push minimum frame rates above 60.
At 1680x1050, the Radeon HD 6450 drops below a 30 FPS minimum. But in an isometric RPG like Diablo III, that's still quite playable. The rest of the cards manage to maintain minimum frame rates above 40 FPS, indicating an excellent level of performance.
At 1080p, the Radeon HD 6540 might be considered playable, but it'll undoubtedly run into trouble in more demanding situations. As for the rest of the cards, minimum frame rates are around 40 FPS or better, suggesting a playable experience.
Clearly, Diablo III doesn’t require a beefy system in order to push its minimum detail levels (though you'll want a Radeon HD 6450, at least, to play at 1680x1050).