In the past, the bulk of PC sales came from replacements. I’ve seen PCs being replaced because they didn’t have enough RAM for Windows 3.1, or Windows NT ran too slow on them. Today, I’d rather spend the money on a digital video camera and an additional hard disk. My 1.6GHz processor is faster than I need anyway.
What I like best is that three years from now, I don’t need to feel embarrassed about owning an archaic 1.6GHz P4. It’s enough for me!