It you shut it down, according to Microsoft tech support, the hard drive will wear out and fail much sooner. Do you hear all that clicking in there when you power up from a cold (off) state? That's your hard drive stylus going crazy jumping all over the platter loading all the start-up files, program files, etc. It's a lot of wear & tear on the hard drive. Extend the life of your PC by using Sleep/Stand-by mode. Use "Restart" once a week to reload all the files which helps prevent corruption. My Compaq PC I purchased in 1995 is still going strong, having used the Sleep/Standby mode only all these years. BTW, shutting down only saves an average of 38 cents per month in electricity.