While just about every big electronics store sells specialized microphones for your PC or Mac, most are intended for simple, telephone-like speech demanded in applications like dictation or online calling.
For high quality recorded audio or applications where clear, high-quality communication is a must, users usually step up to a pro-audio microphone. Take for example the industry standard Shure SM58 and Shure SM57 microphones, which have been used for everything from Nine Inch Nails studio vocal recording, to presidential speeches.
Unless your PC came equipped with a very high quality, recording-oriented sound card (which is most likely did not), then you may run into difficulties dealing with hissing noise, volume inconsistency, or even a plain old dead signal if you try plugging your microphone straight in or with a simple adapter.
The easier options, depending on your type of microphone, are interfaces which calibrate the impedance of your microphone and computer inputs.
The “old school” method is utilization of a powered mixer, then plugged into either the microphone or line-in input on the back of your computer. Adapters will usually still be required no matter what interface you use, as most high-quality mics utilize the XLR connection type. Some use 1/4″ cables. Either way you may need to use an adapter to convert this to 1/8″. Companies like Behringer offer popular and cheap mixers for these types of jobs, and while you do get what you pay for (!), a gigantic mixer has no use for this task.
If adapters aren’t your thing and you’re ready to go all-digital, then you may consider devices designed specifically for micrphone and instrument/PC connection which use USB and USB 2.0 ports. The interface itself allows you to plug your mic straight into the box, which usually comes with simple controls like a volume knob. The output of the interface then plugs into the USB port of your computer, sending the computer data representing the clear, live signal without going through the circuity of your soundcard. XLR to USB microphone interfaces range from extremely compact and simple adapters like Blue’s “Icicle”, to products from brands like M-audio, offering not only mic compatibility but a multiple inputs/outputs and included recording software.
Look around online for the option suiting you best. For most people, a USB interface is the most direct approach. On the other hand, a good mixer (after you make sure whether your mic needs power or not!) can both be cheaper and more multi-functional, in case you need it for actual mixing some day.