Do you isolate your old Windows PC's on their own wireless network? Security is always a concern of mine with less trustworthy devices. For example, I do not permit anything running Android on my WiFi network.
Really? Is this a joke? Why would you not permit anything running android on your network?
This is such an odd behavior seen mostly in people who only use Apple tech. They have been so brainwashed by the marketing by Apple they think they are 100% secure using a Mac.
The world has changed and threats to MacOS and iOS have become more prevalent,
What you need to know about the dangerous Android banking trojan that's been ported to iPhone
www.tomsguide.com
This is a recent example.
Security and privacy on the internet are an illusion at best. You can take steps and have layers of security but if a hacker is good enough it doesn't matter the platform or device as long as it is connected to the internet.
Windows comes with its own highly customizable firewall if skilled enough to use it. It has one of av test higher rated antivirus and anti ransomware built into the OS and works really well and doesn't impact resources. You can monitor your internet traffic with Windows firewall and lock down processes or apps that are not supposed to be talking.
Any OS can be vulnerable to malware. It is about how many tools you can use and how transparent is your network traffic so you can be sure of your privacy and security. Locking down telemetry on Windows is easy.
On Android the OS is open source and audited by third parties. Google has its own security team and has alerted Microsoft and Apple to threats before they knew. Google has very good security on modern phones by major OEMs. Samsung has Knox enclave and secure folders that even iOS doesn't have.
If you want to be secure and private you need to have access to what is going on, then you need the knowledge and tools to lock things down as best you can and then some type of security software. A VPN or Tor network can give you better privacy than any device can by itself and Google offers a free VPN with a Pixel phone. Does Apple offer a free VPN? I don't know. I am sure you can pay for one but free means more people will use it and it gives better security from day one you start using it. You can use Google VPN on your tablet, PC, and phone.
But yes, Android and Windows are just so insecure. LOL
Oh I almost forgot. What do you mean by old? Most PC's old enough not to run a supported version of Windows would not run very well and most would upgrade. Of you just have an ancient PC lying around the best advice is Linux. Ubuntu can be installed and run well on most Windows 8 type PC. Anyone running an unsupported version of Windows is crazy or any OS for that matter, but specifically Windows. Better to let that version of Windows 2000 to die or use security software and hope for the best. Lol