The computer I use is a first generation Apple G5 Power PC, of the type first released seven years ago in 2003. At the time, Apple charged over $2000 dollars for it and touted it as the most revolutionary and powerful personal computer ever. That didn't last long. I bought mine, in almost new condition, three years ago for just a few hundred bucks.
My computer has about the same power and capabilities as last years cheapest model net book. It's a lot less portable.
The good thing is that most people do their computer tasks and surf the web on these little net books with no problem. My seven year old behemoth works just about as well.
I figure it will be at least 2 or 3 years before I need to get a new computer. $400 for a computer you can use successfully for 5-6 years is a pretty good deal.