Some usable free antivirus for Windows XP x86-64 (2003)?

[McSteel]

McSteel: new OSes are also swiss cheese full of holes, what's the difference? old systems with hundreds of updates at least have most of them patched, plus the less ppl use them, the less interest to actually penetrate it so the remaining ones are no longer interesting for them hackers; anybody who's installing latest windblows (where M$ itself spies on the users exponentially more in each new generation) on day 0 talking about better security is just idiot IMO, that thing has hundreds of holes and M$ has no chance to win the race to fix them sooner than they somebody takes advantage of them, especially when hundreds of milions fool are eager to get hacked as soon as possible, all installing it right away; plus there are all the other compatibility issues…I'll never understand these ppl

Actually a friend of mine and I have been collecting data on M$ spying of Windows 10, and the amount of telemetry going out is staggering. No contesting that info.

However.

Win XP is running on so many ATMs your head would spin. It is also used extensively in the military of many countries and other organizations with considerable inertia to change. Besides, even if the usage rate is at about 20%, that's still a heck of a lot of PCs, especially for botnet considerations, because zombie machine exploiters don't really care about much else besides sheer numbers.

Sure, the newer OSs are more likely targets for industrial espionage, but you don't actually care about that, and nobody cares about your machine that much (except botnet creators/maintainers and cryptolockers). But the security vulnerabilities are being actively patched, and for XP and 2k3, they are not. Whatever gets found out, will stay in the wild forever, unless you're planning to manually create a patch. The number of available exploits is increasing daily and the chance of one of them being used nearly exponentially.

But hey, as I said, I'm offering a fair warning. Please do feel free to ignore it at your own peril. As for any modern AVs made for XP/2k3, you can forget about it. No serious AV company is going to stand behind a dead OS and take the responsibility of keeping it safe; it's Sisyphus' work and bound to get them in trouble unless there's enough fine print in the EULA to sink a battleship.

[Behemot]

It is not running on ATMs. The PoSReady 2009 (it's not Piece of Shit, is it?) is running on ATM. I of course have all the systems I use with ordinary XP kernel, umm, upgraded to PoSReady 2009. Which is under support till 2019 :P I don't remember if also XP x86-64 could be turned into PoSReady, have to try…