The recent interest and growing popularity of commodity-based cluster computing has created a demand for low-latency, high-bandwidth interconnect technologies. Early cluster systems have used expensive but fast interconnects such as Myrinet or SCI. Even though these technologies provide low-latency, high-bandwidth communications, the cost of an interface card almost matches that of individual computers in the cluster. Even though these specialist technologies are popular, there is a growing demand for Ethernet which can provide a low-risk and upgradeable path with which to link clusters together. In this paper we compare and contrast the low-level performance of a range of Giganet network cards under Windows NT using MPI and PVM. In the first part of the paper we discuss our motivation and rationale for undertaking this work. We then move on to discuss the systems that we are using and our methods for assessing these technologies. In the second half of the paper we present our results and discuss our findings. In the final section of the paper we summarize our experiences and then briefly mention further work we intend to undertake.