Here's a follow-up to David from Israel's article on Linux. I encourage your readers to heed David's advice and wean themselves off the MicroSoft Windows operating system ASAP.
Linux Mint Debian is a good OS option. See the Linux Mint Debian tutorial. Here is a description: "This tutorial shows how you can set up a Linux Mint Debian 201009 desktop that is a full-fledged replacement for a Windows desktop, i.e. that has all the software that people need to do the things they do on their Windows desktops"
According to this article, the the Chinese military have already removed Windows from their computers for security reasons:
Another potential replacement for Windows is PC-BSD.
These Windows replacements are free as in freedom and free as in zero cost.
Enjoy! - Rick H.