It depends what the processor does with each cycle.

Here is a list of processors and their performance http://www.cpubenchmark.net/cpu_list.php

A Pentium 4 3GHz (an aged processor) is rated at 491, a modern top of the range processor (i7 3GHz) over 10,000 - 20 times the performance. The most lowly Intel Atom processot you could buy would be at least twice the performance of a P4 3GHz.

Any new computer you purchase will have a processor that out performs the specification required by the game.

Simon