I'm running Win98SE, but that's not the problem. The original version of SwapNut (1.0) ran fine for me also, although I certainly prefer the smoothness of a client written in C++ as opposed to java based programs. In my opinion, java is a great language for web sites but not for independent applications.
All of my remarks refer to the new version of SwapNut that has recently been posted for download. If you see nothing to complain about, install and evaluate it for yourself.