Many years ago, people advertised new code releases on Freshmeat. I don't know if that's still commonplace anymore. (I just read their about page, and it seems to be more for Unix-orientated and cross-platform software projects. If your software is more for Windows, there may be better forums.)
Another thing I just thought of is the licensing aspects of your code. Again, I can't speak for the Windows open source crowd, however, in Linux circles, generally your code must use GPL, or at least a GPL-compatible licence, to get much traction.
Good luck with growing your project!