First, shut the computer down and unplug it. With a standard mouse, unscrew the bottom and remove the ball; blow dust from the casing and wipe the ball and interior with cotton swabs dipped in rubbing alcohol. Let dry, replace the ball, and close.

Now turn over the keyboard and gently shake it; clean between the keys with a special computer vacuum or a few blasts of compressed air, then wipe with a microfiber cloth moistened with all-purpose cleanser.

Give the same wipe-down to the computer exterior, and finish by wiping the screen with a cloth moistened with plain water.

Datavac PC Personal Cleaner, $28 at Office Depot, www.officedepot.com, 888-463-3768. Personal-size Mystic Maid microfiber cleaning cloth, $7, www.mysticmaid.com, 877-468-0888. Compressed air, about $6 for a 10-ounce can at hardware and electronics stores.