Looking for protection for my Win7 Ultimate 64 bits laptop

So basically, i really want to protect this laptop since my whole childhood is in there... Any free antivirus recommended for Win7 Ultimate??

The choices are limited by what still supports widows 7. Avast and Bitdefender are the ones people here seem to use, but most just use Mic. Sec. Essentials. Same definitions as Windows 10 gets, and rated close to the others. And no nags to upgrade to a paid version.

i really want to protect this laptop since my whole childhood is in there

Please tell us that you have at least one reliable backup copy of all the documents, photos, videos, etc. from your childhood that you do NOT want to lose.

If the ONLY copy you have is in that laptop, it is disaster waiting to happen.

What happens if that laptop gets lost or stolen or its storage drive fails?

I keep the original hard drive on a box, but i also borrowed a usb flash drive from a friend, where i copied most of the important things to paste them on my windows 10 computer

The first question is, as always, protect against what? What are your fears? What do you want to defend against?

Alejandro is right, what are your browsing habits? What is your paranoia level? Do you plan to take this machine online? If you just want it as an archive, and keep it offline, you don't need any AV. Although MSE is always a good idea. you may need to go online briefly now and then. If you do plan to use it online a lot, how safe are you? Do you have a large exposure to many sites, lots of emails, etc? If so, MSE at least. If your concern is very high, then paid AV would be best.

What makes sense to me with older machines with Windows 7, is to keep them offline by default, use MSE, and update and scan if you go online. But do your heavy web work on another machine, which is up to date. I recommend Linux Mint, Debian Edition (LMDE). You may never go back to Windows again, unless you have a specific need. With me, it's music. I use a digital audio workstation, or DAW, called Reaper. While I can use it on Linux, it's a lot easier on Windows. So I use Windows 7 for that, with MSE, and minimal online exposure. I use Mint for everything else. I sleep well at night. (Well, not really, but that's another story).

Answering to Alejandro and Michael, I want to protect specially the os for when I want to go diving on my childhood, the files are mainly safe, since I got a copy on my windows 10 computer, I'm not that scared because I can just download another windows 7 and paste the files, but idk, I want to keep everything I've done to that os, I've used it on my main computer for 10 whole years

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Answering to Alejandro and Michael, I want to keep the os safe, files are protected on my main computer, but I want to keep all the work and love I've put in there for 10 years of using, im not very scared since I can just download another windows 7, but I still wanna keep that one safe, I think I'll run a lot of malware scans since like 95% of accounts and passwords I've made all across the internet were created and saved in that os