Moore's Law is a high-tech rule of thumb that says the speed of a computer microprocessor doubles about every 18 months, while its price is sliced in half. Basically, that means every couple of years, your computer hardware is going to be out of date, at least in some sense. What matters, of course, is not whether your computers is still the fastest in town but that it's still doing the job you need it to. Typically, after two to four years, a computer truly is obsolete because it will no longer run the latest version of the software you use on it.
Excerpted from Grow Your Business