Honestly, I agree with jay_nar2012. I'd just keep it for a backup system, personally.
You could part it out, but you won't make more than $50-75 total off of it, so it'd just be better (in my opinion) to just hang onto it.
The thing is, I just built my own computer at the beginning of summer and I already got a 500GB external drive (for backup and such) aside from my 1tb HDD, so I don't really need a computer that's 7 years old D: . So I guess I'll go for the 50$ if possible!
I'll think about it a little more about it. Thank you for your time!