I know that for me personally, Windows has outlived its welcome. While Windows XP is probably the best, most complete OS I've ever used, it's too much for me. It eats up my bandwidth, it monitors my actions and reports home, it's very tighly integrated with Passport, another Microsoft tracking system, and it costs hundreds of dollars. With so many other OSes available, about two years ago, when the decision was between Windows 98 or 2000, I began testing out new OSes. Considering FreeBSD was not an immediate decision - I had to warm up to it. And necessarily so. Though FreeBSD is often logical, even advanced and adventurous Windows users will face a fairly steep learning curve.
I am going to assume, for the purposes of reaching a reasonable conclusion, that if you are reading this, you've already either installed a non-Windows OS, used a non-Windows OS, or are a glutton for pain and suffering. Either way, I will take a few seconds in each section to explain the basics, so bear with me.
FreeBSD is not the only OS based on the original BSD design.
In a nearly offensive slimming of their worth, I'd sum up the *BSDs as follows:
* FreeBSD is an all-puprose mainstream OS for the masses.
* NetBSD is designed to run on more platforms than any other BSD - at the time of this writing, 46 platforms are supported.
* OpenBSD is designed to be the most secure OS, out of the box, in existence. Because of this, a lot of the OS is disabled by default, which makes this not the best choice for Unix novices.
* Darwin is another option. According to the website, "What is Darwin? Darwin is the core of Mac OS X. The Darwin kernel is based on FreeBSD and Mach 3.0 technologies and provides protected memory and pre-emptive multitasking. Darwin runs on PowerPC-based Macintosh computers and a version is also available for x86-compatible computers."