I'm not sure why this is in the CFD forum but if you're advertising or giving away software then there's a better place than this.
For your information the program Qplot didn't work as there was a missing dll file. Why should anyone want this when you can use excel? Is there a distinct advantage in using this program?
Used plot3d for most of my CFD plotting. Klunky at times, but it has a lot of capabilities (streamline tracing, grid plotting, contour and vector plots, etc.).