I've compiled a little list of things that need to be done regularly to computers. I am trying to get into a routine of this hopefully a couple of times per month.
1. Update your OS with all patches.
2. Scan your computer with updated virus software.
3. Schedule and run scandisk.
4. Schedule and run a defrag.
5. Scan for spyware/adware. Make sure these programs are updated.
6. Uninstall unused programs, especially if you downloaded freebies.
7. Backup your My Documents folder. This typically contains most users' documents.
8. Empty the Recycle Bin. Yes, it takes up space, too!
9. Run cleanup utilities such as disk cleanup or CCleaner.
10. If you're up to it, image your machine and store the image on a network storage device or CD/DVD.
11. Clean up and back up your email accounts, particularly if you use Outlook or Outlook Express.
12. Clean out your temporary Internet files, as well as any temp files. Some of this will be done with disk cleanup.
13. If you use wireless encryption on your home network, change your passphrase or security phrase.
14. Dust off your keyboard and inside of your computer with a can of compressed air. You can do this every 2-3 months depending upon your environment. Schools are very dusty, so once a month is probably a good choice!
Regular maintenance on your computer is just like changing the oil on your car. It can mean the life of the machine.