The User-PC computing system (UPC) has been studied to provide a parallel computing platform for members in a group using idling computing resources in personal computers (PCs) of them. UPC adopts the master-worker model where we have implemented the programs for the master on Linux and for the worker on Linux and Windows. However, the current job scheduling method does not consider the real performance of a worker PC. In this paper, we implement a function to measure the performance of a worker PC using two benchmark programs. The experiment results for six PCs in our group show that there are three times difference in the CPU performance and eight times difference in the disk performance.