Used a Performa 6200 as recently as July 2000. Then bought an iMac DV 400. Replaced that with an iBook 700mhz in April of 2002. Then bought an iMac G4 700 in October of the same year. That's four right there. Oh, I also have a Powerbook 190 (or 150?) that my parents bought in a yard sale a few months ago. It's running System 7.5.5.
I'm hoping I can wait for the release of an iBook G4, or the second version of the PB 12". Better yet, I want to try and wait for the release of the next processor. iBook G3 700 (current computer) does cover my needs, though.
but my reason(s) for not doing so is because my imac does everything i need it to. it works great, it isn't falling apart (knock on whatever is handy), and i still like it - almost as much as the day i got it.