Let me ask a dumb question.

I bought a Dell laptop on Ebay with Ubuntu pre-installed. It was an old machine
and is awkward to work with now, but I really liked the experience. How easy is
it to get an all-Linux machine and the heck with Windows? Why pay for a software
which I don't really need?

Now let me really expose my ignorance: Is there a way of getting a machine
without an OS and installing Linux on it? Why pay for someone else to install a
free program?