We examine the velocity overshoot effect in strained Six on Six-Ge1-x heterostructures. We also investigate the performance of surface-channel strained-Si MOSFETs for devices with gate lengths representative of the state-of-the-art technology. The Ensemble Monte Carlo method, self-consistently coupled with the 2D Poisson equation solver, is used in the investigation of the device performance. Our simulations suggest that, in short-channel devices, velocity overshoot is very important. In fact, when velocity overshoot occurs, it greatly affects the carrier dynamics and the current enhancement factor of both surface-channel strained-Si and conventional Si MOSFETs.