Skew group algebras of path algebras and preprojective algebras

We compute explicitly up to Morita-equivalence the skew group algebra of a finite group acting on the path algebra of a quiver and the skew group algebra of a finite group acting on a preprojective algebra. These results generalize previous results of Reiten and Riedtmann for a cyclic group acting on the path algebra of a quiver and of Reiten and Van den Bergh for a finite subgroup of $\text{SL}(\text{C}X\oplus \text{C}Y)$ acting on $\text{C}[X,Y]$.