Or if one's willing to learn the OS, it can be used by booting from a CD (live session) or installed to disk. The great thing about booting from live CD is that it's a great way to make secure transactions, the reboot flushes all data. Tahrpup is one of the most popular.
While the numbers of these computers are dropping as though hot coals, there's diehards that'll run their older computers until the wheels fall off, or cannot afford a new(er) model, so Linux MInt Xfce (or most any Xfce based LInux) are a good choice. It's also a good choice for the tens of millions of low cost, low spec, Windows 7 computers (mostly notebooks) with a low amount of RAM & low grade CPU, there's both 32 & 64 bit choices.
While Puppy is a bit harder, especially with the install process (I've not done this), have used the bootable CD's to make secure transactions, in fact to this day, I still use the latest Linux MInt MATE media in this manner for that purpose. Nothing is written to disk, there's zero chance of Malware (on the computer's end) of one's information being compromised, even if the PC is loaded with infections.
I still remember my first computer, a notebook, when I got it, had every bit of 256MB RAM (128MB x2) before upgrading to it's max. Slow experience to say the least, had yet to hear of LInux, if I had, would had been running it longer than I have. Am a 8+ year Linux Mint MATE user, would have been at least 17 years total, had I known of Linux then. It's fast on slow computers & runs as fast as greased lightning on low spec modern models. If one has a 64 bit computer, by all means, download that version.
Megamanx, those Pi 3's are far more powerful than seems at first glance, there's a few who uses these for streaming movies, this brand op miniature PC's has taken off like a jet since initial launch, and the specs are also getting better with each. new release. Much better than any of the Intel Compute stick also.
I admin two large Linux groups on Facebook 65,000 and almost 90,000 users and it's my experience that the vast majority of people fall into one of the following. Lemming (follows the general consensus even if it's wrong), the typical user (tech noob), Wanna-be Sorta-Expert (see Lemming, but a little smarter), Expert (very few of these that have professional experience or certifications). Linux is great because it's open source and the small market share give it the perception of being more secure when in fact it's far from it. Linux is simply last probed and prodded for vulnerabilities to exploit and there is just very little profit in attacking it compared to Windows.
Wow. Linux viruses; have yet to see one of those. Guess I'm not running it enough hours to get attacked etc. Recently my Ubuntu, and my Mint Cinammon both crashed on 2 separate hard drives in my test machine. Wish I could blame a virus or malware; but I get no messages, except the grub loader b&w prompt on the crashed Mint hard drive! Hah! I am one as you know that thinks that just because I haven't seen a Linux virus doesn't mean they don't exist. They are certainly alive and well on Macs & iPads, though urban legend states on a ton of websites that they are definitively NO viruses on Macs. Most experts or IT pros know this isn't true of course, as we've personally experienced seeing and having to remove them first hand. Most noobs will blame any kind of failure on a new OS, but of course they don't know enough to test their hard drive or RAM sticks to eliminate hardware failure from the equation.
Maybe I stepped a bit too far above by saying 'zero chance of Malware', should had been 'greatly reduced', I apologize for any confusion created by that comment.
Yes there has been Linux security holes found, although one thing that the open source community does that the closed source doesn't, all of the major distros puts their differences to the side, thousands of volunteers gets into action & a fix is shipped within 24-72 hours most of the time. Google never gets that 30 day (or whatever) grace period to publicly point out security non-fixes with Linux, as they sometimes (wrongfully) do with Microsoft.
Not that I'm siding or taking up for the latter, it's just that no one should be publishing these details, this creates a field day for Malware distributors & it's outright irresponsible on the side of Google for publishing these details. Fortunately, Microsoft doesn't retaliate in the same low blow manner & Linux devs keep a lid on issues until post fix. A few has gone for over a decade before discovery, hopefully from Malware distributors also.
All of that stated, perhaps the #1 reason why we seldom see Linux users looking for a way to cure infections, is it's low usershare. If Linux jumped to as little as 5% of the total, then more attacks would be launched. However, it's still harder for a Linux system to become infected, as any executable file has to be signed off on by typing in their password. This is even required for the updating system, and there's no showing of the passwords. If a Terminal is ran (same as 'cmd' on Windows), one won't even see the password being typed in, if the wrong one happens to be, will be prompted to retype the correct one.
The only near 'bulletproof' OS is one that either is never booted, or used offline only, a common practice within manufacturing facilities, and optical drives/USB ports are removed/blocked off to prevent sabotage. Some of these may be in a ventilated locked cage to further restrict access. Still, if one has the motivation, any OS can be infected by one with the right skills, regardless of brand, and another reason why Power over Ethernet should be disabled (or use wireless only), it's a backdoor to be exposed.
Hopefully this clears up my typo or knee jerk reaction above.