Many of the top distros (Fedora, Suse, Debian) do not require any real special knowldge to use them. You'll learn the basics of it just like you did in windows. There will come a time when you will want to invoke the power of a terminal. This is when the real learning begins. I suspect the best answer to your question was given in the first reply, find the one which supports all of your hardware, suits your needs and you are comfortable with proceeding on. Try many, it won't kill your hard drive if you install, or if you prefer, live distros to try it out, which will not write to your hard drive at all. A live distro is an operating system that works and runs from your cd/dvd device. You won't be able to save anything to your hard drive this way, not without making some modifications anyways (which your live distro will have instructions of howto), but this will give you a great starting point.