Computing demands for science and technology calculations, business use, and imaging techniques are continually rising. Grid computing that uses idle resources is discussed as a platform for such applications. Grid computing is a distributed technology that has High-Throughput Computing (HTC) as its principal objective. Moreover, several middleware solutions are offered as open source software, and thus a grid has the advantage that it can be constructed at a lower cost than a cluster. However, in current grids, it is not possible to use PCs running Windows OS. Therefore, we have chosen to use a virtual machine. In this paper, we compare a Linux grid of virtual machines with a similar Windows grid.