We offer a variety of stepper drivers in our shop for use on Pololu-compatible slots (i.e. Megatronics, RAMPS, RADDS etc.) or externally using a step-dir-enable interface. Most important is the microstepping, the number of steps for a full step of the stepper motor. A bigger ratio (1/32 to 1/256) reduces noise and increases resolution. But the downside is that the microprocessor has to do more work, which means that for higher resolutions the CPU becomes the bottleneck. The following links may help you compare the different products.