As soon as you drive the car out of the showroom, it becomes a used car, and its value goes down several thousand dollars. A powerful computer is desirable, yes, but it won't keep you from the need to upgrade. Even the finest generation of computer technology lasts less than a year without modifications. A 133MHz Pentium system may be only 50 percent faster than a 75 MHz Pentium system. That's because there are a lot of other limiting factors.
Memory is a prime example.
You may be better off buying a 75MHz Pentium system with 16 megabytes of RAM than a 133 MHz system with 8 megabytes. It just doesn't make sense to buy a computer today without planning for tomorrow. Today's speed demon is tomorrow's slowpoke. If you're looking to get the best value for your money, look to the middle of the pack. Know thyself, as Plato said.