I feel similarly. You might give Ubuntu a try. It's becoming an increasingly viable Windows replacement.
Here's a good list of distros, with pros and cons for each one and similar ones to consider.
Also this tool to suggest a linux distro.
I've tried Ubuntu in the past, but always had trouble with Apple's hardware. Probably going to look further into it again at some point to see if compatibility has improved.
Linux doesn't need a lot of system resources to run well. You could buy a used PC off Craigslist, pop in a new hard drive, and have a fresh Linux PC for you to tinker with.
Anything made in the lase ten years will do. I've ram Virtural machines with less power than that