Surprisingly very few users perform any maintenance to their PC's at all. Quite often after a bit of general cleaning, de-cluttering & checking you will find the pc works faster & smoother.

Liken your PC to a car.

If there are recalls due to defective car parts from the manufacturing process the manufacturer will contact you to have them fixed, on your pc have auto updates turned on, so when Microsoft find problems in their software (believe you me they find plenty) you are notified of the updates needed.

On a fairly regular basis you top up the oil, fill the washer bottle, check the tyres, on your pc this is like running anti-virus & checking for ads etc.

Most people give the insides of their car a vacuum out & throw away the accumulated rubbish, well on a pc this would be using disk clean-up.

At least once a year you give your car a service well surprisingly your pc also needs servicing i.e. clean out the dust & debris inside. (Only do this if you know what you are doing) would you service your car?

First things first:

1: Download or ensure you have the following (links or direct downloads available form the essentials page) these are all free. Why pay over the odds? The only advantage of some of the commercially available programs is convenience because they are usually integrated into 1 program.

These should then be run 1 at a time checking for updates when each program is first started. This is essential to ensure thorough cleansing. If due to a bad infection you are unable to download the latest updates, run the program anyhow & then try updating.

2: When you run the programmes delete all found problems. I have not found any items that should not be deleted. (If you know better please email me)

With all the above installed & system checked run "Disk Clean-up" from "Programs" > "Accessories" > "System Tools"

3: Update Windows. "Start" > "All Programs" > "Windows Update"

4: Run disk defragmenter "Start" > " All programs" >"Accessories" > "System tools" > "Disk Defragmenter"

I will be adding to this listing over the next few weeks.

The following points are for the more technically minded or for those who want to delve deeper

Hard Drive checking:

Hard drives have gotten so reliable that we tend to take their health for granted. But that can be dangerous, because we may miss the early warning signs of trouble. Instead, take a few minutes to check on your drive:
Open "My Computer." Right click on the C: drive, and select Properties/Tools, and then click "Check Now" in the "Error-checking status" dialog area.

In 2K/XP, a "Check Disk" dialog will open. In that dialog box, select "Automatically fix file system errors." Also select "Scan for and attempt recovery of bad sectors" if you have or can make the time for this more lengthy test; otherwise leave that box unchecked. Click the dialog box's own Start button to launch the disk check tests: You usually will then get a warning dialog telling you that Windows can't complete the tests until you reboot; and asking if you want to postpone the test until that time. Select "Yes." Repeat this process for any other disks or partitions you have in your PC; and when all have been scheduled for a disk check at reboot, manually restart your PC. One by one, Windows will then check each disk or partition to whatever level of thoroughness you selected, and will repair any correctable errors it finds.

 
In Win98/ME, when offered a choice of the type of test to run, select the "Thorough" test if you have or can make the time; otherwise select the "Standard" test. In either case, check the "Automatically fix errors" box. Windows will usually be able to complete the tests without a reboot. Repeat this process for any other disks or partitions you have in your
PC. If necessary, you also can run the same tests from DOS in Win98: Restart your PC, hit F8 after the system beep, and select "Command Prompt Only." When the command line is available, type "scandisk /all /autofix /surface" (without the quotes) to thoroughly check and repair all drives in the system. Omit the "/surface" for a faster but less thorough check.