There's no real shortage of processors and graphics cards these days. For every application and intent of building, there's a CPU and GPU that will fit your needs, and budget.
What's also equally apparent these days is that CPUs are very fast, relative to what was available just a few short years ago. This isn't to say that today's CPUs are significantly faster in clock frequency however--they're faster overall and significantly more efficient. Even Intel's Pentium 4 CPU was able to reach current CPU frequencies no problem.
When CPU clock frequencies were sub-gigahertz, overclocking brought in a significant boost in speed ratio. But today, with high frequency processors, overclocking doesn't nearly bring in as much, relatively. However, it must be said that getting more bang for your dollar is mainly what this is about, and squeezing every bit of performance from our components means a lot more than just the bottom line.
The question of the day is: Do you overclock your computers?
If you do, what kind of cooling do you use?
If you don't overclock, tell us why as well.