For the last 4 yrs that i had my MacBookPro, I always put it to sleep after finishing. My OS is Snow Leopard. Been repeating same process everyday. I only shut it down if I go for holiday. Yesterday i sent my com for battery change and the vendor advised me as far as possible try shutting down at the end of day after used. His reason is to preserve the moving parts as mine is a HHD. So far its has been 4 yrs and without any problem by putting it to sleep. Is his reason valid?