With the release of Apple's operating system OSX 10.5 I knew the jig was up. Some new features of last-year's operating system were non-functional on the older Power PC (PPC) versions of the iMac. I had a Power PC. That started my savings plan.
When OSX 10.6 came out a couple of months ago there was no PPC support. Not unexpected. The old machine served me well for almost 4 years. No major surgery; system rebuilds. It just ran. It will now be retired to the entertainment room as a music player and photo display.
It is replaced with a new iMac, configured with a 27" screen, an Intel i5, a quad core machine, and 8 GB RAM. Lots of room to grow. While memory and CPU utilization were pegged with PPC, this one reports lots of capacity.