Leaving It On or Shutting It Off

Q. Is it better to turn off the computer or can I just keep it on all the time?
A. The question about whether it is better to shut down your computer at the end of each day or to leave it up and running has been raging for years, with concern for both the computer hardware and saving electricity factoring into the debate.
One older argument for leaving the computer on was that turning it off every night and starting it up again in the morning caused strain on the hard drive - because the magnetic heads that read and write information inside the drive had to start up as well, and could damage delicate parts. But the hard drives in most modern computers park their heads when the computer is turned off, and starting back up is a much safer process than it used to be.
It does take an extra bit of electricity when the computer pops on after being shut down, but the amount of power is less than what would be consumed if the machine was left on continuously.
Leaving the computer on - and linked to the Internet with a high-speed connection - all the time can make it more vulnerable to infection and invasion by intruders. Even if the machine is turned off every night, though, security programs like firewall, antivirus and antispyware software should be installed and updated regularly to help keep the computer safe when on and online. (Macintosh machines are currently less vulnerable to viruses and spyware, but Mac OS X comes with a firewall worth using.)
You obviously save electricity when you shut down the computer after you are done using it, potentially around $100 a year depending on your system. Turning your machine off at night also clears up items in the computer's memory and gives it a fresh start in the morning, which may make it appear less sluggish if you generally have a lot of programs running over the course of the day.
If you are torn between leaving it on or shutting it down, consider the third option: setting the machine to hibernate or sleep for the night. The computer uses minimal power in this state, but starts much faster than if it was started up cold in the morning.
Web Surfing Without Leftovers