What have you done so far with linux? As a first step, I would download a live CD or live USB and take linux for a spin without installing it. If this is your main computer, I wouldn't just jump in until you're a bit more comfortable.
If the machine is old or a secondary machine, go ahead and jump. You'll learn a lot. You might pick a distro near the top of Distrowatch as lots of people use them and you'll get online help a bit easier. Or if you have a friend who uses linux, maybe pick the same distro they have so they can help you out.