What exactly are Linux and Unix, and what sets them apart from Mac
or Windows. What are their special features, and why do I hear about so many "types" of Linux? Thanks a lot.
A GNU/Linux Distribution is an operating system that is loosely based on the UNIX Timesharing system that was made back in the early 70's for mainframes. In some ways, Linux is less useful than Windows because of all of the software written specificly for Windows, however, Linux is probably orders of magnitude more flexible from a user interface and day-in-day-out use standpoint (once you know how it works), and is the perfect choice if you want to set up a low cost server, though if you have thousands of dollars to throw around a commercail UNIX distribution is still a better option, and there's zero reason to invest in Windows Server unless you *really need* exchange support.
That's probably a terrible answer, but the best I could do in a paragraph. Both Windows and Linux have their own advantages and disadvantages, and I have both installed on this box (though I'm in Linux a great deal more, and only boot into windows to play games that don't run in linux). However, if you are what you consider a "Windows Power User", and you've been using Windows a while and you don't have a naturally inquisitive personality, you're probably going to be confounded by all the new things you gotta learn to be as functional in Linux as you were in Windows. However, once/if you get past that initial hurdle, you'll find yourself a capable, versitle and fun to use operating system.