It's sometimes really hard to gauge just how much progress has been made in the silicon world over the past few years. The problem with most benchmarks is that they are used to compare the latest stuff with stuff that was the latest a few minutes ago. However, the ever-useful The Tech Report has put together a benchmark of CPUs ranging from the monster Core i7 975 "Extreme Edition" all the way down to the lowly Pentium 4 670.
Note: The Pentium 4 670 is a single-core 3.8GHz part dating back to around May 2005. Here's a good review of the CPU when it was released.
The results are, quite honestly, breathtaking. Some highlights worth checking out:
Well worth a read, even if only to see how far things have come along since 2005!