If you purchase a PC, make sure that it comes with a graphics card or graphics accelerator to speed up graphics on your monitor. Most do, however, ask the salesperson to verify. If you care to take advantage of the audio capabilities of the WWW, you may want to purchase a sound card and a pair of computer speakers. Sound cards are add-on modules that give your computer the expanded capability of playing audio files. Finally, it is desirable to have a mouse.
Most new computers come with a mouse.
I've been through the pit-falls of not knowing what to buy. I hope you find the above information useful. Setting a common standard for Internet communications allows a multiplicity of software and hardware to communicate freely. An analogy would be a meeting of foreign leaders from France, Italy, Spain, Israel, Great Britain, and the United States. There are a number of methods of connecting to the Internet, some of which are clearly superior to others.