Cleaning the outside of your PC
To start with, what you need is a lint free cloth, a can of compressed air, cotton swabs dampened with water, tweezers, and perhaps a little isopropyl alcohol. Definitely do NOT use ethyl alcohol or cleaners that contain acetone or ammonia on the monitor if you are using a flat screen display. You should also avoid using a vacuum cleaner for any cleaning since it might damage the computer. Finally, before you proceed with the steps below, turn off the computer and monitor (in fact all hardware you are cleaning), and disconnect all cables.
1. Wipe the outside with the cloth and use the isopropyl alcohol to remove any persistent stains. Although the inside could probably benefit from having the dust blown out of it with the can of compressed air, opening the case might terminate the warranty so perhaps this is best avoided. For a laptop, just blow the compressed air over the keyboard. Whatever your system avoid blowing air over the fans in case you create a power surge.
2. Wipe the screen gently with the cloth (lens cleaning cloths are perfect). Don’t press hard on the display as you might cause damage. If there are any more resilient marks on the monitor use a cloth, or cotton swab, lightly dampened with water or isopropyl alcohol. Be careful when using any other cleaning agent on the monitor since many of these will damage the LCD. You should also avoid spraying or pouring liquid directly onto the screen.
3. Turn the keyboard upside down and tap it from the back. Then use the compressed air to blow off any remaining dirt. If you have a laptop, just blow the keyboard with the compressed air (avoiding the fan slots). Then use the cloth, tweezers and cotton swabs to clean the keys.
4. Wipe the mouse with the cloth. For a roller-ball mouse, open the bottom cover and clean the rollers using cotton swabs and tweezers or your fingernail.