WXSIM runs on any Windows-based computer (as far back as XP, though with a couple of limitations in Windows XP and 7) and is a free download, with Atlanta, GA and some other sites as demos. It's a clean, compact installation, with all the program and data files in one folder. I, Tom Ehrensperger, have been working on this software for 37 years (yes, really!) and it's my sole creation, though others have helped a lot with data provision and thrid-party scripts for display of WXSIM's output on web pages, plus LOTS of ideas, bug reports, and feature requests over the years. The primary thing you are purchasing if you order it is my time and effort in developing customized data files that enable full, site-specific operation for your exact location. WXSIM is innately a very large, complex system, with a huge array of options, BUT I've streamlined much of this and developed options for the program to run automatically; so, while there's plenty there for the "pros" to play with, it's also accessible for beginners, and everybody in between! Please explore the site via the top navigation bar to learn more about a tool the likes of which you won't see anywhere else!