I happen to know the starter of this thread, Goftrey, quite well. He loves his older machines, as do many others in this thread. The shear fact that he can upgrade his ram is part of his determination to keep it alive for a few more years. His Powerbook is currently running Leopard with 512Mb of ram. Leopard is still a modern operating system that is still very able. While it runs with 512Mb of ram, it runs much better with 1.5Gb. At the time Leopard came out, 1GB of ram was the average for Macs.
Even if he will never get the ram cover off, he'll still use that Powerbook as his main portable. Many people in this thread use 6+ year old Macs as their main/only machines. zen.state's PowerMacs are over 12 years old and they get daily use as his main machines. The extra money Goftrey is investing into his machine is peanuts compared to a new one. If he can get two more years out of it for ~£20, he'll be extremely happy.