Cygwin is a Linux-like environment for Windows. It is sufficiently complete and stable that porting even very large codes to the environment is relatively straightforward. Cygwin is easy enough to download and install that it provides a convenient platform for traveling with code and giving conference demonstrations (via laptop) -- even potentially expanding a code's audience and user base (via desktop). However, for various reasons, Cygwin is not 100% compatible with Linux. We describe the major problems we encountered porting Rice University's Open64/SL code base to Cygwin and present our solutions.