What/how to upgrade this computer...

Jeez mate, just buy or build a new PC...the only good thing about that one is probably the case and that probably doesn't have a PSU or cooling fan capable of coping with any upgrades.

 

Honestly, Linux should be in everyone's teacup. It is the bee's knees to resurrect old to ancient hardware. The thing is, why would you spend money on something when a new OS makes the computer *like new* again? Obviously, 4GB of RAM is better than 2 GB, and cheerful for Linux.

 

Um, because you don't want to spend the time to learn yet another operating system, if you're not going to use that for anything else?

 

For sure, but you were getting aggravated over a slow computer. Windows 10 is not going to make it run faster (Not taking the mick on Windows here) so what do you have to loose?