Unless the activities on your computer are restricted to pure textual output (plain text files), your computer is going to get filled with a lot of "stuff" - stuff that can overfill a PC's capacity too much for the computer to function well.
The problem is that while upgrading a computer is always an option, technology advances so fast that newer products (such as memory chips, new drives, etc.) aren't always compatible with the machines that we own. Sure, one could upgrade the operating system to accommodate the demands of a new piece of hardware, but trouble starts when that new operating system requires new hardware in return. Today's "older" computers are perfectly capable of accommodating the needs of young PC users, and they're excellent machines for playing educational CDs, small multimedia files, or games downloaded from the Internet. Convert the machine into a storage area. As you can see, old computers still serve a purpose either for you or for someone else. And although selling an old computer is always an option, there are a number of things that you can do with an old computer. The one huge concern for many when it comes to selling a computer it what happens to the data on the machine. Find out what you can do to protect your old data.
You can reformat the drive. . This way it's harder to find the old data if not making it impossible.
. It will delete a file permanently instead of leaving traces of it on the drive.