A Pentium computer will generally be much faster than the old 486s. Pentiums come in speeds ranging from 60mhz to 266mhz. New computers today are usually Pentium 166s or faster. The higher the number the faster the speed. As well as a computer, you need a modem.
Some computers come with an internal modem.
Others don't and you have to buy an external modem. An external modem is a good idea because it is easier to replace or upgrade. Whether you go for an internal or an external DON'T buy anything slower than 28.8kbps. Ideally you should go for a 33.6kbps. The faster your modem, the faster you can move around the Net.