I use a Powermac G3 operating system version 8.6 at work and at home use a two-year-old Mac G3 (beige model, pre USB ports) running operating system version 8.1. This weekend I attempted to upgrade my home G3 to 8.6 and received the the following error message: "This program cannot run on your computer. See the documentation for more information."

Please tell me that this doesn't mean I'm stuck at 8.1 unless I buy a new machine. (The machine is only about two years old and I had hoped to get a few more years use out of it before I invested in a newer model.)

If there is a way to load OS 8.6 on my home G3, how do I do it?

It sounds like you took the system disk from the newer G3 at work and tried to install 8.6 (from that disk) on your home computer. Unless you had the same models, Apple can't let you do that. You would have to go buy the full-CD from somewhere. Then it will work on ANY computer, home, work, etc. Good luck.