This isn't just a program, it's an entire operating system. You would have to format (or at least alter) your main PC to install this Artist .9 suite.
No, there is no virus. As opposed to the Microsoft/PC world, Linux users don't have to worry about viruses.
There are hundreds of different "distributions" or "distros" of Linux, and all of them are free. Programmers work on these programs (and operating systems) in their spare time, to develop their skills, add volunteer projects to their resumes, etc.
I've installed many "distros" on extra PCs in years past, and I've never had any problem with viruses, etc. That's one thing you don't have to worry about.
To Joan Scholastica -- you'd have to pretty much give up Microsoft Windows and any Windows programs you use in order to use this Artist .9 suite. I recommend testing it out on an old PC you have lying around first. There are equivalent programs in Linux for most popular Windows programs -- but they take getting used to, of course.
Matthew