Computers are typically used for a wide range of situations which range from mundane work tasks to more pleasurable endeavors which are essentially entertainment based. Although many of the cheap laptops under 100 dollars provide an excellent source for the work and play uses, it is a good idea to make sure the laptop will provide the necessary functionality in order to accomplish what it is that you need it to do for you in your situation.
Mainly any of the laptops are going to be capable of the basic computing tasks which include things like web surfing, email, creating and storing documents and spreadsheet and a number of multimedia operations as well. This is the good news and as a general rule of thumb so to speak, when it comes to used laptops under 100 dollars it is best to have 512MB of minimum memory if the computer is running Windows XP as the installed operating system. This will allow the laptop to operate at a consistent level of responsiveness while you are multitasking. This is basically anytime you are doing more than one thing on the laptop at the same time.
As long as the computer has sufficient hardware it will remain reliable in its performance under most conditions. Of course working laptops need to have antivirus software installed on them in order to help keep the software side of the computer running efficiently. Luckily there are several really good programs which will accomplish this and they are free as well.