Windows NT
The third version of Windows was a solid operating system. It was not a challenge for Macintosh yet because Windows 3.1 wasn't quite up to snuff in the graphics department. However, it was a 16-bit operating system, and by the early 90s the hardware demanded a software upgrade. This brought about Windows NT, which was intended mainly for servers. The NT operating system shows its strengths in intranet applications. Windows NT (Windows version 4.0) was designed for use in servers and on networks.

Windows NT is a robust operating system that can take advantage of NTFS (New Technology File System), which on most computers tends to be more stable than FAT (File Allocation Table) file systems; this is because there are essentially filters that prevent the computer from corrupting data. For a number of reasons, such as price, size, system requirements, difficulty of setup, and the fact that Microsoft made it hard for consumers to get Windows NT, it was not very widely used in home computers and other small networks. In larger networks, it remains quite widely used because of its relative stability.

Windows 95
Developed around the same time as Windows NT, Windows 95 shares a similar interface with NT, but that's where the similarity ends. Windows 95 uses a different kernel that's not quite as robust as that of Windows NT. Windows 95 also can't take advantage of NTFS. Windows 95 brought several advancements to the Windows line: the 9x kernel and a more advanced, graphical UI (User Interface) that most people could find understandable. Windows 95 was also the last version of Windows developed without the Internet on the top of developers' minds. In some distribution Web browsers and email, clients were included; however, the OEM (Original Equipment Manufacturer), not Microsoft, often supplied them.

Windows 98
Windows 95 and Windows 98/98SE are very similar operating systems; however, there are a number of differences. Windows 98 has several advancements including vastly updated drivers, integrated Internet browsing software, and full support for USB (Universal Serial Bus), a plug and play (digital) serial connection that offers high connection speeds, hot-swappable connections, universal connectors, and an extremely easy setup process.

With a free download from Microsoft's Web site, Windows 95 can have the integrated browser too, so I would call this advancement a draw. Windows 95 has limited support for USB because it seems that Microsoft added it almost as an afterthought, and as a result, most USB enabled products won't work with Windows 95. Windows 98 corrected this problem, and all USB enabled devices should work if you have USB ports on your computer. Windows 98 inherits the kernel from Windows 95, and as a result, it's not as robust as it could be. But it works. Both Windows 95 and Windows 98 are intended for consumers. However, they both work well in a number of other situations.

Windows 2000
In late 2000, Microsoft updated NT in an operating system known as Windows 2000, while technically it's Windows NT 5.0. Only the Help "About" file refers to it as such. Everything else refers to it as Windows 2000. Windows 2000 Professional is a very stable operating system that operates well on workstations and equally well on individual computers. It has all the benefits of NT with the new features of Windows 98. Windows 2000 Server is essentially Windows 2000 Professional, except that it comes with software for running Web servers, intranet servers, and terminal servers. Some people also report that it's slightly more stable, though I haven't noticed any noticeable increase in stability.