Question: My computer is slow. My computer has 1 GB of RAM, 80 GB HD and a P4 processor.
Answer: There are some maintenance procedures you can perform on your computer to try and speed it up again. I would begin by doing some cleanup of your hard drive and remove any temporary files stored on your computer. You can use the Windows built in Disk Cleanup tool to do this. A better option is to use the free Ccleaner program which will find and clean things that Disk Cleanup wont. It also has a registry cleaner which will help cleanup unnecessary registry items.
Next I would check your startup items using msconfig and uncheck anything that you don't want starting with your computer. Many programs configure themselves to start with your computer each time it boots and most of them are not needed and use system resources and slow your computer down. Just be sure only to uncheck items that you know are not needed. You can look up items online if you don't know what they are used for. The changes wont take affect until you reboot your computer. Then you can check the box that says don't show this message again for the system configuration utility that will appear after the reboot.
After that you can defragment your hard drive. When a drive becomes fragmented it can slow your computer down because it takes longer for the drive to find the information it needs. Its a good idea to do this every month or so.
Finally I would check for spyware infections since they are notorious for slowing computers down. You can use free software such as Spybot, Malwarebytes and AdAware or there are effective programs you can buy such as Spyware Doctor.