[This is MY opinion, not that of the mods. Mods: if you feel uncomfortable please delete this - I wouldn't want anyone sued!]
To some of the earlier posters: bluntly, you're daft if you use XP connected to the internet and don't install the updates. Microsoft don't do them just to give programmers mental exercise.
And it affects all of us if YOU don't keep your system fully patched. If you are subsequently the victim of cyber crime, we all pay for the clean-up costs. If your machine becomes part of a "botnet", you will be indirectly be responsible for others suffering the same fate.
Personally, I hate Microsoft products. In the 1980s I watched MS change from a keen, competitive company into a behemoth that had a very lucrative monopoly. IMHO it's worldview hasn't much changed since those days. If it could still be the bullying, arrogant outfit it was in the 1990s, it most certainly would be.
I have a long, long list of Windows annoyances* found at many different levels within it, and I would stop using it immediately if I could. That is impractical for the time being. One of the biggest issues is that Windows networking (by which I mean LAN Manager originally), and its multi-user functionality, started off with what many consider to be a flawed security model. It's different from UNIX-based systems, including Mac OS, iOs, Linux and Android, and requires a VERY good knowledge of the security side of the thing to be able to lock it down properly.
I remember sitting in training courses in the early 1990s, alongside UNIX and Novell experts doing "LAN Manager conversion", whilst a Microsoft trainer tried to (a) explain the inexplicable, and (b) justify the architecture to an outright hostile audience! We all thought, "They'll revise that - they'll have to." But they never really did.
Most Windows XP systems run with the logged-in user having Administrator privileges, meaning any breach of their security exposes the whole machine. You can alter this, but that's how it's shipped, and still how most people use it. Basically, you have to restrict users under MS, but you
grant rights under everything else. If an attacker penetrates a domestic Windows XP machine they often have access to everything. If they penetrate a normal Linux account, they usually have access to almost nothing important beyond that specific account - the damage is contained.
Computers aren't toys. Nowadays they're ever more intimately linked with our daily lives, and a security breach is catastrophic for individuals and even capable of destroying large companies. The breaches we see in big outfits are usually the result of mistakes in programming custom-built applications, or human factors such as corrupting a knowledgeable individual so as to gain access, or requiring inadequate proof of user identity. In other words the weaknesses come from how the systems are used. Rarely are they through weaknesses in the underlying operating systems, Linux being the preferred choice, with a well understood security model.
The huge advantage of open source, too, is that there is no commercial incentive to hide flaws that are detected. On the contrary, kudos goes to whoever comes up with the best fix fastest. When software is proprietary and a flaw is found, there is ALWAYS a discussion about admitting the problem and fixing it, versus leaving it be and handling each incident as it arises. It might be reputation or simply programming resource allocation ("if they're busy mending that, they can't be developing this!"), but the debate always happens at some level in the outfit.
It's remarkable, after all this time, that MS are STILL having to release patches to XP. IMHO, it tells me all I might ever need to know about the security of the original product. But...
... If you use it, it doesn't change the fact that you ARE vulnerable if you don't patch it when MS say you should.
Stay safe out there.
E.
*O'Reilly published
a string of books with that title. They always used to use line drawings of appropriate animals on the covers of their technical series. The drawing for that book was of the Warty Toad.