A recent serious Windows 10 malware "bot" incident here reminds me again that seniors and all versions of Windows are magnets for such attacks. A bot can not only bring down a computer but also a network and infect other computers. That is scary.
More and more senior users "just say no to Windows" and use almost anything else, like an iPad, or Kindle or Google tablet. A lot less learning required, too.
Chromebooks are actually impervious to such attacks because the inner workings of the computer are not held locally and vulnerably on your local machine's memory at all. Chromebooks work just like your browser.
Now that your old computer can be used as a Chromebook or converted with a $5 flash drive, that would be a cheap alternative. Tap or click for how to do it at http://www.neverware.com/free/#freedetails
Disclaimer: I use (and like) Windows (10 only now) but use it only occasionally, with care, encryption active, VPN, security and updates enabled and current.
Microsoft recently announced a coming security improvement in keeping your version of Windows up to date by automatically updating it to Windows 10.
For more about Chromebook security, Tap or click for http://www.mobilegeeks.com/chromebook-virus/