The "popular" Linux brand these days is Ubuntu; it's user-friendly enough (read: GUI interface, configuration, etc) that most people can get by with it, but not shackled with some of the proprietary restrictions of Microsoft products. Although, it should be said that Linux, at it's heart, runs on configuration files, most of which are human-readable ... if you get into enough trouble, you will be forced into the position of having to edit these by hand; Windows isn't too different in that respect, but it is much less concealed with any Linux operating system than it is with Windows.
Also, be aware that there is no "official" support mechanism for Ubuntu/Linux like there is for Windows; there are support mechanisms, but not in the traditional sense; something to be aware of.
On a more technical note, it is also worth noting that what you are used to running on Windows does not work on Linux; yes, there are usually open-source alternatives, but be clear about that word: alternatives. They are not compatible. The classic example is the ubiquitous *.exe file on Windows; these file types mean nothing on Linux, and any Linux (or *nix, to be more specific)-based OS will not run them - at least, not without help (e.g. WINE). So, that favorite game you want to play? Probably won't work, because it is built specifically for Windows. Do your research into this, and be absolutely clear about what it means when .exe files won't run on Linux.
Another issue is the driver support for new(er) hardware; because Microsoft dominates the OS market, hardware vendors always release Windows drivers first ... and then, only maybe, after thinking about it for several months, do they release Linux versions. Granted, it is a lot better these days than it used to be, but if you live on the bleeding edge of hardware releases, any Linux-based OS may turn out to be your worst nightmare. And, on that note ...
Graphics manufacturers, such as NVidia & ATI (or AMD, whatever they call themselves these days), generally release closed source video drivers that will install binary versions of their drivers, which goes against the open-source philosophy. However, most Linux users view this as a tradeoff - the ability to use a newer graphics card, against the privilege of having open-source graphics drivers. Sound drivers are slightly less shackled, but not by much.
Also, note that Microsoft Office has alternatives on Linux, but that does not mean that they are fully compatible; code you write for an Access application, for example, will probably not translate 100% to an OpenOffice (or OpenLibre) application without help. That is not just applicable to Office, but to many, many of the "classic" Windows applications.
All that being said, if you do any sort of "real" programming (C, C++, Perl, Java, Python, basically any real programming language), Linux will actually make your life easier; the GNU toolchain is practically built right into any Linux OS (by virtue of the kernel, and various other required components), which means that you can program in several languages "out of the box", in a much more intuitive way - as opposed to Windows, which seems very abstracted from any sort of "native" programming element(s).
Finally, familiarize yourself with what a "Linux operating system" really is: two components, one of which rarely changes, and the other of which is arbitrary. It is always the Linux kernel (version may vary), and then it is a layer of programs (scripts, shells, etc) which build up an environment that the user interacts with (almost always including the X window system). So, what I am trying to say here, is that depending on how far you "drill down", you will be in that top layer of the Linux "flavor" that you run, or you will be in the guts of the Linux kernel and it's associated components. That is an important distinction to make when you start tinkering with your system.
And, more finally, the X Window system; I could write an essay on that, just by itself. Read about it, and learn about window managers - specifically, KDE and GTK, which are the most commonly seen. However, there are many people who offer their own flavor of Window manager. You'll have to experiment and find out which you prefer.
And, absolutely finally: historically, Linux (and any *nix system) has had a huge problem with library inter-dependencies; Microsoft has this problem a little, but because the development is coordinated by a single company, the reality of the situation is somewhat opaque. To crystallize the situation a little more, let's say you wanted to install a library that enhanced your desktop a little bit (say, by adding Googly Eyes to your taskbar) - well, maybe that depends on a library released by MIT, which depends on a library released by Berkeley, which depends on a library released by Joe S, which depends on .... so on and so forth. Ubuntu (and other "newish") Linux distro's include software managers that simplify this issue into a "point and click" interface, but occasionally, they will foul up, and you will wind up with a broken system because a library got removed that was embedded in some fundamental dependency chain. This is when that problem of no "official" support mechanism becomes important; however, you can usually find an answer on a forum somewhere - assuming your system still boots, that is.