Apple

If you just want to run emulators on it you may want to consider installing linux on it. Considering the fact you only use windows the learning curve shouldn't be any worse than OSX and you can install a newer version. You could also install a dedicated emulation distro like lakka, but then you can only use it for that, it has no desktop.

You can install a more modern MacOS with OCLP. Not my main machine, but I installed Monterey on a 2011 iMac without SSD and it runs, though it’s slow, but fine for some purposes.

You've got two different questions in there, I think. One of them is "what's so great about mac" and the other is "what to do with an old mac"?

It sounds like you're likely to be frustrated finding out the answers to the first one on that machine, though for some people a Catalina OS on a form factor or model they really like is sublime. If you're just trying out the os from the Windows side of things, it's not as fun because there's some learning curve stuff that's just annoying to get through at first. Command-key vs CTRL, but Command-key is the Windows key on some keyboards so -??? stuff like that.

As for the "what to do with it" question, I'd argue the form factor would answer it. for an iMac, I'd think about a music station, maybe find some good visualization programs (there was a milk plugin for VLC I found awhile ago that I liked). A browser / emailer / kbinner is good if you have the keyboard and mouse you like. Or, if you just want to put it on a shelf and look at it's coolness, a digital photo frame. The last iMac I saw my friends had in their kitchen for music, recipes, youtubes etc.

If none of those interest you, then yeah running Linux is always an option and a darned fine one. Make it the killer Kali seekrit station or whatever :D

Depending on the actual hardware, 2011 vintage is still enough for the computer to run decently.

You might want to bump up the RAM, but it's young enough that it might still be a decent computer.

Did it dump a disk image on your desktop? Click it and it’ll open a finder window. Grab the app icon and drop it into your applications folder.

Also I second the commenter who said install Linux on it. You’re going to need to hack it together anyway, may as well get the latest software in return

Apple's support site has a few articles that you might find helpful. A good one to start with is "What’s it called on my Mac?" which matches Windows terminology with its comparable Mac version. Another one is "Mac tips for Windows switchers" which outlines the Mac OS way to perform common tasks. But if you poke around, you can find a bunch of interesting stuff to check out.

You also can try to install some minimal Linux distro and run some Pihole, Plex, Jellyfin, homeassistant, etc.

I’ve got two 27” 2011 iMacs and I still use them for the kids as browsers/media players/old games. The mobile GPU isn’t amazing, but the i7 version I’ve got plays half-life 2-era games decently. Would definitely recommend sticking an SSD in it if you’re going to use it regularly. Just be aware that the spinning drives have a temp sensor on them that won’t be on an SSD but there are some easy workarounds for it. It’s a great machine for learning (a slightly older) version of Mac OS, or you can install Linux or Windows on it.

For $15, might as well just have some fun with it! If you know linux/unix at all you’ll find the terminal very comfortable, and many of us find that once we’re used to osx it’s hard to go back to windows.

Would that newer operating system even be feasible on such an old system, though?

Not really. Apple is leaning hard into high speed low latency flash memory file storage and modern OS version are just not optimised for the HDD in your iMac. It'll be a little better if you install an SSD... but compared to a modern Mac it's still going to be about 10x slower in terms of bandwidth and even worse than that in terms of latency compared to a modern Mac.

The latency is the real killer - when Apple switched form Intel CPUs to Apple Silicon CPUs, a lot of disk benchmark tools started showing "zero" or sometimes even negative values for file access latency, because it was so fast they weren't even able to get an accurate measurement. Apple has optimised their software to pretty much require that speed.

Your 2011 Mac has a disk controller chipset on the hard drive, which talks to the CPU over a SATA interface that was barely fast enough for a spinning metal hard disk drive. Modern Macs have the disk controller inside the CPU. And PCI connections to flash memory chips right next to the CPU (almost part of the CPU).

You're better off sticking to older versions of MacOS which had more caches in RAM than the newer versions. Or, you could put Linux on it.

You haven't wasted your money at only $15. But you also haven't really got yourself a proper Mac either.

Not a serious answer but your question brings this video to mind, specifically at this time. Jumpscare warning for the timestamped link: it starts right after a loud portion but stepping forward cuts off the start of the next segment. It's also a bit older so the quality isn't perfect.

Catalina runs perfectly on my mid 2009 macbook pro so it will run fine

I appreciate all the advice you guys are giving me!

By the way, I should probably mention that I do have an SSD in this system, along with a SATA Y-splitter to keep the CPU fan from running at full blast all the time. Seems to work so far! I wish I could have secured it with screws rather than a few pieces of Gorilla Tape, but whaddaya gonna do.

Linux probably would be easier for me; I have a little more experience with it than Mac OS. But I feel that it would be a good idea to just learn how a Mac works. I imagine that knowledge would come in handy later. Prior to this, I owned a chunky Power Mac made in 1996, and I can see that the Mac operating system has changed a LOT since that time.

Plex media center/server would be a good example of what you can do with it. As people keep saying, you need to drag the app inside of it into the applications folder, the thing showing on your desktop is the image, kind of the exe installer. When you’re done copying the app, drag the thing in your desktop to the trash to ‘eject’ it.