Generally it is a good idea to replace your computer every 3 to 5 years. However, if you are only using your computer for simple tasks such as browse the Internet or simple word processing, then, you can keep your computer for many years, as long as all your computer parts are working.  However, if you need the latest multimedia capabilities or to play the latest games, make home movies, or connect to the latest gadgets, then you definitely need to keep your equipment up to date.

Unlike your car, computer components generally don't "wear out" because it has very few mechnical components. But computers do break down from time to time. When a computer break down, sometimes it is cheaper to buy a new computer than it is to replace the broken part.

Generally, the few mechnical parts in the computer break down first: The keyboard, mouse, and cooling fans. Then the power supply, hard drive, CD/DVD drive. Processors and memory don't usually go bad if you had your computer running for a while, but occasionally they do go bad due to overheating because the cooling fan went out. Motherboards sometimes will die as well due to the heat issue.

Today, you can get a decent computer for less than $500. But these low cost computers may not be able to run the latest games or multimedia applications. Also if these low cost computer use cheap cooling fans, it is also more likely to break down the system.  A typical mid-range computer cost around $800 and a higher end workstation with the latest bells-and-whistles could cost around $2000.

If you have a 4 year old lower end computer system, and you are lookinig to get faster performance, the first thing you should do is to check if you could add more memory, or add a bigger, faster hard drive. Adding more memory or a hard driver costs far less than a new computer system.