Back in the early days of computers, processor speed was incredibly important. The difference between a 1 GHz processor and a 1.5 GHz processor was noticeable, even to novices. Over time, the importance of clock speed has become ingrained in all our minds. But nowadays things are a little different. As Ars Technica points out, comparing clock speeds between processors isn't as important as it was 10 years ago:
In a nutshell, the Pentium 4 took many more clock cycles to do the same amount of work as the original Pentium, so its clockspeed was much higher for the equivalent amount of work. This is one core reason why there's little point in comparing clockspeeds across different processor architectures and families-the amount of work done per clock cycle is different for each architecture, so the relationship between clockspeed and performance (measured in instructions per second) is different.
For the most part, we've reached the point of diminishing returns for clock speed on desktop computers. Which is to say, unless you're editing a lot of video or buying a laptop, you don't need to spend the extra money on more processor speed. For speed improvement, your money is best spent elsewhere: If you want to speed up your rig for gaming, you're best off buying a better video card, and if you want to just speed up general performance, a solid state drive will boost your speed more than a new processor.
The point is that when you're looking to buy a new computer, or if you're interested in upgrading yours, the processor is likely the last thing you need to consider unless you have special, processor-intensive needs like video editing.