You have a problem. Either you should have upgraded your 486dx2 before installing windows xp, or you may some form of “spyware” on your system.
Spyware comes in many forms. Usually it is packaged with frills programs such as screen savers, instant messenger add-ons, etc. It monitors your computer usage and usually gives you some sort of advertising popups now and then.
Sometimes, spyware can do worse. Sometimes it will monitor keystrokes in order to capture passwords, user names, and web surfing habits.
In any case, spyware can significantly slow down your computer. These programs usually do not have a simple way to remove them. Instead you need a program that will search out spyware on your computer and destroy it.
Many people, including many technology blogs on the internet, recommend installing Spybot Search and Destroy. It is a free program that can detect spyware, shred files, and more. Many computer services departments are making this a must have product for all computers they work on.
It is easy to use, and requires a relatively low computer skill level to operate. In the end, you computer may run a lot faster if you use this program every couple weeks!