Right quick, here's what I use (together):
--Malwarebytes: For general malware scans, though the latest version's scan is, like, 90% faster, and it leaves me wondering if it's lost its thorough scanning ability, so I might start looking for a new option.
--CCleaner: Dumps crap from your registry, browser (when it starts chugging from months of temp files and cache data), and other programs well.
--Revo Uninstaller: Good for removal of nasty programs and for making sure that when you uninstall a program, it's 100% gone. Some programs will leave registry files and other crap behind, and it can be annoying.
--Spybot: Kind of hangs around for seniority, but I did have an instance not too long ago where it turned out to be the only thing known to remove a specific browser highjacker from a relative's laptop, so it gets to hang around for a while longer on my PC, just in case.
--Windows Defender: The first 4 programs, those are used situationally. None are run real-time on my PC (though I think that they can ALL be left running full-time, at least MWB and CCleaner definitely can). Windows Defender's good enough for real-time protection, I guess. At least, it's better than nothing.
Windows Defender is enough for most people, how is it not doing a good job keeping windows secure?
You don't need a 3rd party antivirus, antivirus companies still play the fear card for naive consumers
For the love of whoever has to deal with malware on your PC if you get it, IGNORE THESE PEOPLE. Windows Defender basically exists on everything you buy nowadays. However, as the person who serves as family (and their friends) IT, it is NOT good enough on its own. My mom recently had me do clean-ups on a couple of friends' laptops. One took maybe 5 hours with the aforementioned MWB and Revo to clean up. The other took around 15 hours of repeated scans, as it had upwards of 300 infected files the first time through and more than 200 the second time. It was a hellish nightmare. As I also stated, I had to get a browser highjacker off of my brother-in-law's laptop a while back as well, and Spybot ended up being the only solution to the problem I found.
There are enough free programs that can do SOMETHING to help you, like the ones I listed. There's no excuse to lazily leave a computer so barren like leaving Windows Defender (which, while it's shown improvement, still hasn't matched the competition) as the only line of defense. Trust me when I say that no one wants to spend 15 hours running virus scans and OS restores on your computer because you thought the built-in stuff (and never actually doing your own maintenance with it) was enough.
Oh, and since my mom just had this happen and almost had a stroke freaking out (even though it's nothing):
When those stupid pop-up things come up and say you've got a virus in your browser, THEY'RE NOT REAL. Hers, it brought up a blue screen of death as the scary warning (that only comes up on older versions of Windows when the OS crashes; that it'd appear in a browser is a hilarious giveaway that it's fake), and some audio file on a loop kept telling her she had a virus. When these kinds of things occur, it's pretty simple to stop:
1. Open Task Manager (Ctrl+Alt+Delete or right-click the Start button)
2. Find your browser in the Programs tab
3. End the browser process. (side note: when you're on Firefox or Chrome and ads pop up and slow down your browser, if you don't have AdBlock, you can do something similar in the Processes tab and kill the Adobe Flash process to stop most ads and not harm what you're doing, unless it's YouTube-related)
4. When you re-open the browser, it'll be gone, but the browser will probably ask you about restoring your last session. Given how that session ended, don't do it. Close the browser normally again, then re-open it. You'll be fine from there.
Last point: It is at a point where getting a virus isn't a thing to constantly fear. I mean, I run manual scans when I get bored and remember, which might mean several months, but nothing ever comes up in them. Still, make SOME kind of effort to clean things up yourself so they don't spiral out of control. If the browser is consistently running like crap, run CCleaner, clear it out, and put up with retyping passwords to get some speed back. When you find an errant program on the computer, run Revo on it. If you think you have some malware, run Windows Defender AND Malwarebytes manually. If you're like me, and keep Spybot on just in case, take it out for a jog now and then, to see if it picks up any little spyware annoyances that the other programs don't go after. Whatever you get, make an effort and run manual scans on occasion.
Norton is very resource intensive and tends to slow down a PC.
Yeah, Comcast gives you Norton free with their Internet service (or, at least, used to). It never seemed to be worth the trouble.