Switching from Windows 10 to Mint on an older laptop

My Asus is 10 years old; still runs great, so there's no reason to discard it--especially if it's only going to be used as my secondary PC. I just bought a 250GB SSD to replace my 1TB 5200rpm HDD. I was going to reinstall Windows 10, because it doesn't support W11. Then, I remembered about the lack of security updates. That's when I was reminded...