a desktop computer, after all. Again, it would be best if you can turn the computer on to test, so you can see if all the keys are working and if the pointing device is functioning smoothly.

These are mostly things to look for at first-glance. Usually, when checking out used machines, the first thing I look for is wear and tear. If a computer seems older than it’s supposed to be, then that means the original user might have not taken care of it properly. Or, it could mean that that particular model (or even brand) was poorly built by the manufacturer, and should be avoided.
What’s next?

Let me add to The Dude’s suggestions in determining whether a laptop still has a few years of servicable life. After inspecting the build quality and physical characteristics, do look under the hood. Here are things I would look for.

    * Processor - While old computers still do work, I won’t go with any technology older than five years. For this reason, I would probably not go below anything lower than a Pentium III or the more modern PowerPC G3s. These can still run today’s modern OSes (such as Windows XP service pack 2, Mac OS X Tiger, or your choice of Linux flavor) pretty well. Do consider what you plan to do with the laptop. A P-III should be able to handle wireless Internet and the usual Web surfing, email, IM and VoIP pretty well. Movie playing and MP3s are also handled decently. Don’t plan on playing around with multimedia manipulation, though. You’ll need raw processing power for that.