I fix old computers all the time.
That, or I salvage parts inside of them. If you only have one or two systems, it's a bit hard. But when you get your pick of the litter, before everything gets e-junked, you can do some fun things. My favorite, was about 13 years ago when people used to trash all of these old pentium pros. With the gold market going up, I held onto a good amount of different components that are worth a decent chunk in gold value. All of it, was just a matter of my own time.
Plus, a lot of old systems make great frisco-type hardware firewalls, and they make good NAS units. The old AT full-towers are trully awesome for installing two low power boards, and running 10-18 hard drives for network storage.