This document provides a summary of a comparative study on the performance of IPv4 and IPv6 protocols under different operating systems. The study analyzed bandwidth utilization, round trip time, and overhead for IPv4 and IPv6 in point-to-point configurations under Windows 2007, Mac OS, and Red Hat Linux. Experiments were conducted between 3 PCs configured for IPv4 and IPv6 communications over an unloaded network with 3 routers and 3 workstations. Key differences between IPv4 and IPv6 such as address length, header fields, and transition mechanisms are also outlined.