Due to Windows NT's widespread acceptance on desktops in business and industry, it is also being considered for use in real-time systems. The fact that Windows NT is a general-purpose operating system complicates its application into a real-time environment. We have performed an extensive performance evaluation of Windows NT to determine if we can use it in the development of future real-time systems. The evaluation involved measuring interrupt and deferred procedure call latencies as well as many other system performance aspects which would affect the performance of a real-time system. The results have provided us with insight on what types of real-time systems can and cannot be implemented with Windows NT.