AMD Athlon XP 1800+
Released on October 9th, 2001 along with the 1500+, 1600+ and 1700+ models. At that time it was AMD's fastest desktop CPU until the 1900+ was released on November the 5th.
The release of the Athlon XP was big news for the computer enthusiasts: it marked a new era for AMD. It was a decent and fast CPU and often outperformed the Pentium 4 while being cheaper as well. It's only real drawback were the bad designed cooling solutions (and system integrators that didn't care for a case-fan) which were noisy.