The term “overclocking” is used only for a processor as only this component can be really modified.
The easiest but the most expensive way to overclock your computer is to a computer shop and to buy a larger amount of memory, to update your processor and, wherever possible, to replace video card. If you still have some money, you can buy much better hard disk. But the video card, processor and memory should be replaced by the compatible components. For example, modern AGP-video card requires the connector of appropriate configuration. If you have an old computer equipped only by ISA and PCI connectors, there will be no place in it for a new video card.
In most cases, the global changing of configuration is not required – `only a bit faster speed for your computer. To do this, you may try a free way for raising your computer’s productivity – to increase the productive features of the current equipment (overclocking) and to decrease the losses of system resources (optimization).
AMD and Cyrix are the least resistant processors to overclocking. It means that these processors cannot be overclocked at all.