Edit: Hehe, just saw this on Yahoo news: http://news.yahoo.com/s/ap/20060430/ap_on_hi_te/apple_security;_ylt=AkXC.TKRXJuqQrIl7Mj0ZjUjtBAF;_ylu=X3oDMTA5aHJvMDdwBHNlYwN5bmNhdA--
Fedora Core is specifically designed for ease of use. You never have to look at a terminal if you don't want to. But you might have some trouble following directions from other people for certain things if you have never done it before and do not use the terminal. But for any command, remember that 'man' is your friend (e.g., 'man man' to see the man[ual] page for man).
Fedora Core is a community supported GNU/Linux project that only provides free software using unencumbered open standards. As a result, many programs like mplayer and xmms are not included (but these can be readily obtained - send me a message if you want me to give you GUI friendly directions for getting MP3, DVD, Flash Player, etc., support). Nevertheless, this means you can use the software included in any way you want, make copies if you want, and even modify the source code and recompile it. All legally.
The majority of websites are run using Apache (free software), often on Linux or another Unixish OS. The majority of Wikis (the software that runs Wikipedia) are run specifically on Fedora Core GNU/Linux systems. Linux is stable enough that when Microsoft was heavily effected by a worm, they used Akamai's Linux servers to proxy requests to their servers (and filter out bad content). To offset the popularity of Linux and Apache in web hosting, Microsoft has requested that "parked domains" (inactive domains with just pages that say "there will eventually be a website here") be hosting on Windows server using IIS.
Mac OS X is Apple's attempt at Unix. To start, Apple tries to hide the terminal (to the woe of seasoned Unix veterans) from view, and make every really pretty. While Apple's GUI is highly polished, it turns out that substantial parts of their GUI are copied from KDE and/or GNOME (which come on the Fedora Core installation DVD/CDs).
Macs have good hardware support because they are only designed to run on a small range of hardware. But Apple is known not to be the most friendly with hardware manufacturers and as a result, "Mac compatible" hardware tends to be excessively expensive.
At Mac OS X's core is Apple's Darwin kernel, an open source Unix kernel based on the FreeBSD kernel. (OS X is Unixish like Linux.)
Next, Apple tried to make the Unix experience more friendly to users by giving everyone elevated security levels (and not setting a password for the 'root' super user). As a result, if you do something stupid, you might cause the entire system to stop working.
Additionally, software support for Mac OS is kind of weak, with the primary inexpensive software being available directly from Apple (and designed to try to get you to buy their $2000 version of the same software - e.g., iMovie vs. Final Cut Pro). Apple prides itself on being a hardware company but does not make any of its own hardware. Apple prides itself on being a software company but licenses most of its code from third parties or uses a pre-existing code base (e.g., Darwin, Safari, etc.).
Microsoft Windows XP is the first really mainstream version of Windows NT. Windows NT has existed since before Windows 95 and was at various points able to run on Alpha and PowerPC CPUs in addition to x86. However, because supporting those hardware platforms was too hard, Microsoft dropped support down to only x86.
Following in the footsteps of Windows 95 and Windows 98, Windows XP includes several proprietary "standards" and partial or bastardized implementations of open standards. For example, Windows did not properly support IPv4 (from the mid-1980s) for several years. Windows support for 64 bit platforms and IPv6 are lagging behind most other systems.
Every version of Windows has more features over the previous versions, and most of these features (according to Microsoft's own employees) are massively bloated and not really written very well. The result is that every version of Windows practically requires substantially better hardware (Microsoft's Vista is coming at the beginning of next year).
Microsoft is notorious for intentionally providing faulty support for things they used to support to encourage upgrading among users. Specifically, there are several different incompatible versions of the Microsoft Word file format. Microsoft WordPad is essentially a crippled version of Word that does not cost money. If you try opening a too recent Word document, you will get an error saying that WordPad does not support that because you had to pay for the full version of Word. WordPad does not support tables.
Microsoft often changes substantial parts of its API without telling anyone, which causes many programs that used to work fine to stop working altogether. This is the case with every major Windows upgrade including from Windows 1.0 through Windows 3.0 and 3.1, Windows 3.1 to Windows 95, Windows 95 to Windows 98, Windows 98 to Windows 98 Second Edition, Windows 98SE to Windows 98 Millennium Edition, (And as was noted earlier, Windows XP is not in the same line as Windows 9x because it is based on Windows NT which existed somewhat before Windows 95.), Windows XP to Windows XP with Service Pack 1, Windows XP w/SP1 to Windows XP with Service Pack 2.
Windows XP has substandard OpenGL support, in Microsoft's effort to encourage the use of Microsoft's own DirectX instead of OpenGL. However, while Microsoft's new operating system was still in the early stages of development, Microsoft was saying that one way that its new OS would be better was that it was switching from DirectX to an entirely new, much better system. Microsoft is not switching from DirectX after all.
Windows XP is notorious for bad hardware support. Switching the port that a simple IO device like a mouse is connected to causes Windows to make a copy of the drivers for the mouse. Additionally, if you do this enough times, Windows is likely to give you an error saying that it cannot find the appropriate drivers for that device.
Windows XP is the only operating system I have ever used that has crashed as a result of a paper jam.
Windows XP borrows high level IO buffering from many other OSes, but also uses excessive amounts of virtual memory whether they are needed or not. The result is that the benefits of the IO buffering are more than offset (a RAM operation may require up to three disk reads and writes) and hard disks tend to overheat to to the repetitive reading and writing.
Versions of Windows are designed around an interoperability method that is, in theory, benefitial to the user because everything should seemlessly fit in with everything else. However, the result is that if one program misbehaves, this can make the entire system unstable. Additionally, a minor bug that would normally never cause a problem, may manifest in unusual ways and be exceedingly difficult to track down.
Nevertheless, Windows is the most popular desktop operating system and is "supported" with a wide array of third party proprietary software products and support services, which Microsoft prides itself on. The result is that some software makers such as Blizzard Entertainment and Ubi Software refuse to provide even moderate support for non-Windows operating systems, and are often late in releasing products to other OSes. Contrarily, some software makers have expressed displeasure at Windows's OpenGL support and provide fully supported versions of their products for other operating systems (like Linux) before even Mac OS.
Some software makers further complain about Microsoft's development tools being incompatible and setting back development for any given platform / environment several months.
So basically how it works is that Linux will run on just about any hardware you throw at it, though the hardware support may be suboptimal. In some fields, Linux is lacking serious software (that is not to say that the support is not there, just that no one has made the "serious" software in those fields). Linux is what runs your TiVo.
Mac OS is a niche OS designed to run only on Apple's preselected hardware, and Mac OS X is designed to be more attractive than functional.
Windows and other Microsoft products were promoted using anticompetitive practices, and Microsoft primarily tries to make their products appear user friendly, even at the cost of functionality and stability.