If you had said "Windows 2000" then you would have had a solid point - this was a turning point providing rock-solid stability (compared to the Win9x/ME series) along with major functionality such as plug-and-play, power-saving, hibernation support, USB support, side-by-side versioning (ending "DLL Hell") and, for business users: Active Directory, Hierarchical Storage Management, software RAID, Encrypted File System.

In contrast, much of what XP added was either trivial or annoying, including:
* Windows Product Activation;
* that stupid search mutt;
* overly-complex Start Menu;
* half-baked implementation of Windows Themes;

More useful additions XP provided were:
* faster startup;
* Shadow Copy Service;
* improved compatibility with older applications;
* FAT32 filesystem support (and exFAT with KB955704);

Fortunately, most of the irritating changes in XP can be reverted (mostly via Registry changes) with Product Activation having numerous bypass options. Vista/7 however made many of those changes compulsory. YMMV - the system this post was typed on has been running the same install of XP since 2007. As long as you maintain it properly (and in fairness, that applies to any OS) you shouldn't ever need to re-install.
The disc cache on XP works fine in my experience (in fact, my problem is that I want to be able to disable it to use third party alternatives) but it will (and should) give up memory to applications. So if you are frequently running applications with high memory usage, that will negate the benefits of Windows file caching.

However you can get an alternative that uses PAE (Physical Address Extension) to access memory above the 4GB limit (up to 64GB) for caching - Primo Cache refers to this feature as "invisible memory" and it can also record cached folders and reload them on the next system reboot (pre-fetch). It can further use NVMe/SSD volumes to cache HDDs (L2 caching). It's one big downside is that it requires online activation.
Sun had absolutely nothing to do with NT - their OS was a commercial Unix, SunOS/Solaris.

Microsoft did initially collaborate with IBM in producing OS/2 - when they parted ways IBM developed their portion into OS/2 2.0 while MS produced NT 3.0. NT's TCP/IP stack was originally taken from BSD Unix but later replaced with MS's own code.
XP's core file system is NTFS which has a file size limit of 256 TB (it'll be a few years yet before disks get that large). FAT32 was a Win9x/ME file system, which XP supported to make migration from those OSes easier.
Win7 requires twice the memory to do the same job as XP, has slower performance for a number of reasons (graphics driver moved from Ring 0 to Ring 1, UAC file/folder/registry redirection, Windows Registry no longer a memory-mapped file, system utilities like Event Viewer re-written using .NET Framework), tightening up on online activation (last time I checked, you had to do a BIOS flash to fake being a top-tier OEM system) and requiring third party software like Classic Shell to get the traditional UI back.
What - removal of support for modems slower than 28.8K? Dropping support for the 486 processor? Hardly a big deal and most of the other examples there can either be reinstated (desktop themes, missing screensavers) or were replaced with (arguably better) options ("minimise to desktop", "align to grid").
Nice try, but the first version of Windows was released in 1985. Or maybe you were confusing it with Unix's genesis in 1969?
Agreed - MS was unforgivably lax on malware until SP2. But this did result in a thriving community of third-party security software, including application-level firewalls, process-control software and a host of anti-keylogger, anti-spyware and anti-trojan utilities that any knowledgable user can rely on to lock down their system (if anything, the danger now is in going over-the-top and running into conflicts between different security approaches).

Plus most of the worst security breaches were in Microsoft applications (Internet Explorer, Outlook, MSN Messenger) so using customisation software like nLite (free) or XPLite (commercial) to remove them and replace them with third-party alternatives is a valuable (and in my view, necessary) security enhancement.
Drivers did, and still do, run at kernel level and a poorly-written one can crash either a Windows or Unix/Linux system. The key thing is keeping tight control of what software can load drivers and Windows XP scores better, courtesy of third party software like Process Guard, AppDefend, System Safety Monitor, EQSecure and many others. Such software has to hook into Windows' SSDT (System Service Delivery Table) to function effectively however and Microsoft have made this much harder with Kernel Patch Protection - so while later versions of Windows can be said to be more secure "out of the box" there's less opportunity for security conscious users to lock them down further.

You’re talking about Windows 2000, right?
Everyone knows Windows 3.11 and Windows 2000 SP4 are the only two versions that have ever been any good for professional use.

Not that either can hold a candle to the One True OS: BeOS

FAT32 remains in use on USB drives and SD cards, though larger drives/cards these days use ExFAT, which is the successor. (ExFAT adds 64-bit file sizes (allowing files larger than 4GB), but takes away the redundant copy of the File Allocation Table (FAT) and still doesn't implement permissions or other fancy features.)

XP was a great deal indeed.

As I remember it, people hated Windows XP.... until Vista was released. Its introduction of online/ phone activation was very controversial and the Luna theme reminded many of fisher-price. Win2k was the one you wanted.

Yes, SP2 and SP3 really helped a lot for the stability, but security still was a joke.

Also you could make your system unusable when installing a bad driver or when the hardware was not compatible. I tried installing Win98 and my sound driver probably about 20 times, before I learned that the motherboard's TX4 chipset didn't support the SB16. When I tried to install it's driver, Windows broke completely.

I totally second that. For a virtual machine it's very useful.

Windows XP had its purpose and if you never ever changed any driver or installed new software it WAS reliable. Many cash terminals used it as operating system for many years.

Q&D DOS is based on the desire for a x86 CP/M. QD DOS/86-DOS is transformed into PC-DOS for the IBM by Microsoft. Microsoft turns PC-DOS into MS-DOS. Windows is based on MS-DOS. NT Kernel is invented but still needs compatibility with DOS.

And so a decision by one of the cohosts of Computer Chronicles comes to haunt the OS some 40 years later.

It's a problem of perspective, IMO. The primary goal of an OS is to provide a standard interface and standard libraries, and pretty much every OS managed to provide this. UNIX based OSes are doing better at this goal, because they're providing fewer holes while doing so. Let's face it: Windows' prominance is the aggressive discount strategy leading the average person to see anything other than windows as a cheap (or overpriced with Macs) knockoff brand. Microsoft and a few other tech companies (Linksys for example) employ the same strategy fairly effectively with course materials for colleges to further lock in their hardware. You see, Cisco, Linksys, and Microsoft all provide their own certifications, now, and we all know how corporations see certification as the foundation of competency.

EDIT: As for this obsession for XP, it's like how people often continue to obsess over the first person they've slept with, even if they're no longer together. Or their first video game. Or their first... you get it. Windows XP was the OS that was around at the time most people got their first computers.

The IBM PC shipped in August 1981. The very first DOS release was for Seattle Computer Product's own S100 system for which: Windows 1/2/3.x/9x/ME ran on top of MS-DOS, evolving from a simple GUI to an OS providing multi-tasking, hardware management and memory allocation - feats well outside the capability of MS-DOS. DOS was used for file access and you could say it played a role - albeit one that shrank with the introduction of 32-bit disk and file access in Windows 3.x.
...which it achieves by using NTVDM, which makes use of stripped down versions of DOS system files (far from 100% compatible, hence the need for the likes of VDMSound and DOSBox). So DOS isn't present and doesn't play the role it did with the 16/32-bit Windows releases.

You could argue the Windows NT family includes code from the '80s, but that's as far back as anyone can go.

It's definitely a nostalgic sound, and I kind of miss it, but that change is something for the better. It's like using 3.5" floppies. I sort of miss that too, but it was replaced by better tech.

Here's a way to test the cache, on Windows:
* First, get a large file, but not too large. (In particular, the file needs to fit in RAM.)
* Second, open a terminal, cd to the directory where the file is, and do
type largefile > nul
(where "largefile" is the name of the file)
* Once that finishes, enter the same command again.

If the disk cache is working will, the second use of the command should be much faster than the first use, because the file should still be in the disk cache.

Also, notice that the file "nul" doesn't appear? That's an MS-DOS legacy feature; nul (in any folder with any extension) is like /dev/null on Linux. Anything written to it disappears, and reading it will return EOF right away.

Try naming a file "nul" In Windows; you'll notice it doesn't work. In earlier versions (like XP), the message you get will typically be one that doesn't make sense in context, but it was later changed to something more informative. (Note that, if you somehow have a file with that name (via something like cygwin or WSL), you might not be able to delete it using normal Windows tools.)

Nope.
DOS uses a lot of system calls from CP/M.

A TL;DR if you don't want to read an entire research paper: And it's those system calls from CP/M that are the problem. This is why a file named AUX or LPT1 is impossible in Windows, because those are special files that exist in every directory, pointing to system calls and device names.

Whirling? Certainly not, it's floppy! Tray? All I hear are magnetic head sounds. But sometimes my 20MB hard drive is louder!

it was very bad , constat problems not stable at all , glad it died

Yes, simplicity it's the main advantage of WinXP. There were a lot of things which were bad but this minimalism is really something that I miss so much.