When you find used computers for sale, you may see this as just an opportunity to get a great machine for a low price. In many ways, this is exactly what it is. A used computer can sell for hundreds of dollars less than a brand new one. However, this does not mean that you should just purchase the first one that you find. There are some things that you need to look out for to make sure that you do not get ripped off. To begin with, you need to be warned that people will sometimes try to sell computers that do not work anymore. These machines could have broken hard drives or broken sound cards. There could be physical damage to the case that makes it so that the computer cannot be used. You need to check all of the components carefully. Make sure that the person is not trying to sell you the computer because they just cannot use it. Make sure that they are not upgrading to a new computer because the old one is worthless. Next, you must watch out for viruses. You do not know what they did with the computer. You do not know what sites they went to frequently or what programs they downloaded. They may have gotten a virus that makes the computer crash every time you try to go on the internet. When they realized what happened, they might have decided to sell it to get some of their investment back. You do not want a computer that has a problem like this. A virus can make it nearly impossible to use, and it can put all of your files and your personal information in danger. The last thing to think about is what you need the computer to do for you. An older computer may not be compatible with all of the programs that you need to use. This is a problem that can make the computer useless to you. Check the operating system and look at the raw capabilities. Do not purchase a used computer that you will not actually be able to use.