In the 80’s and 90’s, computers were making quantum leaps in speed every few years which made old equipment hopelessly obsolete. That progress has slowed, to the degree that a ten-year-old computer can still have a lot of life in it, especially if it’s running Linux.
There are Linux distros that will remind you of good old Windows XP. They take some getting used to, particularly with learning the concept of installing from its own software manager as opposed to downloading install files from the internet.
If you’re intrigued, I recommend giving Mint Linux a try. You can burn its iso file to a DVD, boot your computer up from it, and give it a test drive. https://www.linuxmint.com/