Ah, you all are so kind. I love Chorrol.

Thing is, I can take my box to a shop. That's another two hundred at least right there, and that's if I'm lucky. I can do Google or Bing searches, which means hours go by. And I still might wind up like this this:

I can ask our I.T. guy here at work. This guy retrieved a password for me a couple months ago. It was like magic! I was seriously stumped. But if I ask him hardware stuff, I start hearing a lot of "Um, I think so", "Um, have you tried Google?"
It's so much easier to just ask a question here, and get some good answers.
But first... coffee. Ahh..
Lena: I think it only has one. There's a D drive, but it's always been empty, and now that I've looked in the box, I know why. There's nothing there! I can see the cable which goes to my C drive, and it continues down to an empty slot, but the second connection has nothing attached. Yikes. I always wondered why D seems to have nothing there.
And WHOA... so Windows is on C drive!! See, it's good I asked here first. I was wondering why the drives I was seeing online are so cheap. As you've noted, it's because they are blank. I'm pretty sure when I bought my computer in 2013, it came with Win8 pre-installed. That answers a whole nother set of questions.
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Rosa: I brought the drive to work, so I can see it is definitely SATA.

And that Seagate is close. The number on mine is ST1000DM003.
Hmm, I am assuming an install of Windows would cost extra money, right? Or is that simply free from the internet? I went on the Microsoft site last night and Windows 8.1 seems to be free (probably because it's old).
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Acadian: I don't mind Windows 10 on my auxiliary computer, but there's no way it's going on my gaming rig!

Not after reading hundreds of horror stories (plenty from you all) on how games suddenly stop working!
All: I wonder if I should just buy a new computer? $500 from Walmart, done. Because literally, there was nothing wrong with this one a couple weeks ago. I mean yeah, I can replace the drive in this one, it's actually pretty easy. But then what
else might go wrong? You know?

Maybe the power unit fails? Maybe the motherboard? Next thing I know, I've actually spent more than $500 over the next few months/weeks/days...
Thanks you all.