For some reason the PC assembly manufacturing industry has been historically one of meteoric rises and falls. More so than most industries than I can think of.
The PC hardware industry is one of the few remaining bastions of nearly pure free enterprise. What one vendor does well to gain market share can be relatively easily dupicated by another.
As Capitalism is intended: the consumer wins... and wins... and wins.
As of the 1 GHz Pentium III -- roughly -- the home PC entered what had been the realm of the supercomputer (Cray 1). It takes even less time now for supercomputer power to become average user power than it did then.
How I love free enterprise. :-)