Reputation systems have been a hot topic in the peer-to-peer community for several years. In a services-oriented distributed computing environment like the Grid, reputation systems can be utilized by clients to select between competing service providers. In this paper, we selected several existing reputation algorithms and adapted them to the problem of service selection in a Grid-like environment. We performed a quantitative comparison of both the accuracy and overhead associated with these techniques under common scenarios. The results indicate that using a reputation system to guide service selection can significantly improve client satisfaction with minimal overhead. In addition, we show that the most appropriate algorithm depends on the kinds of anticipated attacks. A new algorithm we've proposed appears to be the approach of choice if clients can misreport service ratings.