

The problem is they may become compromised then used by the bad guys to distribute malware or spam, or as zombies in DDoS attacks. The difference here is that it is important to remember the problem with Vista (and XP) is not just that they might become a security threat to the user. We have all done it with still working CRT televisions and monitors, cassette players, cell phones, hard drives and more. While we all hate to retire hardware that still works, it is just a fact of life.

And if your legacy hardware will not support a modern version of Windows, then you can try Linux, or accept you need to bite the bullet and upgrade your hardware. Well, the obvious is you need to upgrade to a modern and secure operating system that is still receiving security updates.
