Windows

Do NOT use Windows, use a free^[1] operating system like Ubuntu. If you buy a laptop (or any other) computer with Microsoft Windows pre-installed, the license is restricted to that hardware[full stop]. This means that when the laptop dies, you can't actually transfer the operating system to new hardware. If you're laptop dies, you can't use the OS that "came with it" to upgrade an old PC, nor install it on new hardware. If the screen gets smashed, you can't just take out the drive and put it into another computer. You didn't buy an operating system, you rented it.

On the other hand, if you download (for free) a freedom-respecting operating system like Ubuntu, Fedora, or Debian, you could not only put a copy on your other computers, you could give it to your friends, share it with your family, inspect it, adapt it, improve it, and everybody else would be able to enjoy the same freedoms that you have.