A lot of people are wanting to extend the life of their Windows XP machines. What you’re suggesting is not unreasonable, but I have questions about whether or not it’s going to be useful.
A disconnected life is … safe
Unfortunately, in my way of thinking anyway, that machine’s not particularly useful either. It’s limited to what’s on the machine; no more and no less.
It’s fine for playing games, as long as you never want to put a new game on it, as long as you never expect to do any online gaming, and as long as the games themselves never expect to connect to the internet. It will be a fine, dedicated gaming machine.
Storing pictures? Sure, as long as you never add any more pictures to it. It’s a fine machine for viewing the pictures that are already stored on it. The problem, of course, is that putting more pictures on to the machine means that, by definition, it will come in to indirect contact with other computers.
A disconnected life is … unlikely
Do you download your pictures from your phone on to the machine? Well, you can get some malware that way. Do you copy the pictures onto a USB drive and then transfer them on to that machine? USB drives are definitely one way that malware has been known to spread. And if you connect the computer up to a network, even just a local network, you’ve got all the same vulnerabilities as the other computers that are connected to your network.
Basically, any approach that’s going to make that machine useful, by adding more pictures, for example, potentially violates the very security that you’re trying to achieve by making it an unconnected, dedicated device.
It will probably work. But it’s possible that if you want to make the machine useful, then you will still end up being at risk.
To be useful, realize risks remain
My recommendation: just don’t fool yourself into thinking that it’s safe. Either keep doing all of the things you know you should be doing already to keep your computer safe, connected or not, single function or not, or change the operating system. Update to something that’s supported; be it Windows or Linux.
My biggest concern here is the false sense of security…and that once you find out just how limited a disconnected machine really is, the steps you might take next will render it somehow vulnerable.