While the OS('s) are the most important part of the computer software, there will be many people who own original copies of Windows (thanks to a branded pc) but use other pirated software.
I found that there was a freeware substitute to most software available (on both windows & linux platforms) so I dumped MS Office, Norton [and other bloatware] and stuck with the free [better] alternatives. However, though linux is a powerful operating system, some times windows is a little invaluable (for games particularly
) so I had to stick with it.