One of the things I love about Macs is their longevity. It's not at all rare to see a 10 year old Mac (or older) still being used. With Apple's continued move towards industry standards, I suspect this trend will continue, as hardware and peripheral options remain available.

Starting with the PCI based Macs (the likes of the 7200, 8500 & 9600 PowerMacs) Apple opened the door to such popular options as USB and FireWire upgrades. Neither of these were found on Macs of the day