Parallel file systems are widely used in clusters to provide high performance I/O. However, most of the existing parallel file systems are based on UNIX-like operating systems. We use the Microsoft .NET framework to implement a parallel file system for Windows. We also implement a file system driver to support existing applications written with Win32 APIs. In addition, a preliminary MPI-IO library is also developed. Applications using MPI-IO could achieve the best performance using our parallel file system, while the existing binaries could benefit from the system driver without any modifications. In this paper, the design and implementation of our system are described. File system performance using our preliminary MPI-IO library and system driver is also evaluated. The results show that the performance is scalable and limited by the network bandwidth.