1. Windows 1.0 was a graphical shell that allowed the user of an IBM PC to have several MS-DOS programs running at the same time, sharing the screen through viewports called "windows," hence the name. It was released after the first Apple Macintosh computer, and most users did not install it because it required too much memory. MS-DOS was an operating system that could only have one application open at any given time, and those applications could only access up to 640 kilobytes of RAM. Files stored by it had names consisting of eight characters, a dot, and three more characters, and certain characters, such as spaces, were not allowed. TEXTFILE.TXT was a typical DOS filename.
2. ~ 3.0 was a graphical shell that also had dynamic library support, a feature normally built into an operating system. Applications had to be written "for" ~, almost as if it was an operating system. It did things on behalf of applications, like an operating system. It was started from DOS as an application, and exiting ~ returned the user to DOS. Instead of folders, there were program groups, where programs had to be explicitly placed. Placement of a program in the Program Groups typically involved telling ~ the complete path to the program executable (ie, "C:\COREL\WP.EXE")
3. ~ 95 was a graphical shell that was booted directly by DOS, so that it appeared to be the entire operating system. It imitated the look and feel of a Macintosh. It was capable of running most ~ NT binaries, and it implemented pre-emptive multitasking, a feature commonly found in operating systems, and added support for "long filenames" (LFN), which allowed files to have Macintosh-like names. The "Restart in DOS mode" feature is equivalent to the "Exit Windows" feature in older versions of ~.
4. Windows NT ("New" Technology) is a real operating system that was written completely independantly of the line of graphical shells that are also called Windows. Microsoft hired the employees of DEC that designed VMS to work on ~ NT. Unlike ~ versions that were already on the market, ~ NT took full advantage of the Intel 386's 32-bit capabilities. Its design was so closely tied to the Intel 32-bit architecture that it could not be ported to a 64-bit platform easily.
The "New" technology in ~ was new only to Windows. Features new to NT, such as true multitasking and virtual memory, had been available in other operating systems since the 1970s and even before that.
Microsoft eventually began to market Windows NT as an alternative to UNIX, but they did so at the same time that Linux was becoming ever more popular as a UNIX replacement. Windows NT had many bugs of its own, and its superficial similarities to Windows 95 caused users to expect Windows 95 bugs to be present in Windows NT. Its Internet server offerings were notably inferior to the UNIX programs they were meant to replace.
All current versions of Windows are descended from Windows NT, and not from the DOS shells that were also called Windows.
Though 64-bit Intel processors are already available in 2004, a 64-bit version of Windows is still years away.
Architecturally, these are all inferior OS's when compared to their main competition: UNIX and its derivitives (i.e. Linux and *NIX OS's, and Mac OS X). Arguably, they only managed to gain a marketshare because the UNIX community had been in a state of decline in the mid 1990s, and Linux wasn't user-friendly enough to take the market (i.e. there was a power vacuum). All Windows OS's and shells are plagued with numerous security holes inherent to their monolithic design: because all essential parts of the OS's are so tightly integrated, not only is it extremely difficult for a development team to attempt to fix a problem without creating more problems due to the interdependencies inherent to the monolithic structure, but also any security flaws in ANY component of the OS (or shell) could be used to somewhat easily exploit any other system components. This, coupled with the fact that none of the Windows OS's are true multi-user systems (unlike time-sharing systems like UNIX and its derivitives), thus making it easier for a user to do significant damage to the system without using the administer account, makes all of the OS's undesirable for mission-critical applications (including server use), or even for regular internet use. In fact, security analyses show that Windows suffers from so much malware and cracker/script-kiddie attacks mostly for its flawed design, rather than its popularity. One should also note that popularity is only indicative of effective marketing, not quality.
The only "worthy" use for this software is to play games--its large userbase has attracted 3rd-party multimedia programming and hardware development firms more than any other OS in history. Consequently, most hardware in the computing world works or can be made to work with Windows. Even now, this unique feature is deteriorating as more and more developers cross-compile their software for Mac OS and Linux (i.e. NVIDIA Corporation writes a universal driver for their video hardware that will work with Windows, Mac OS, and Linux).
Mac OS X, Linux, BeOS, Mac OS Classic, and other (somewhat) current OS's with merit, however, are either virtually immune to malware (UNIX and derivitives are compartamentalized and modular, making it virtually impossible for a user, or a program executed by a user, to take control of a system without root privilages), or are too obscure to effectively develop software for in the first place.
Each succesive release was designed to take advantage of the new and more powerful technologies available. Or in plain English, the extra bloat in the new version would require more powerful hardware, negating the extra processing power available and cancelling out the benefits of more powerful (not to mention expensive) hardware.
Person B: Why don't you use something else then?
Person A: Like what?
Person B: Linux? Mac?
Person A: Do they support all my hardware and programs?
Person B: Ah.