Re: How often should you turn off your laptop?
Leave your computer on ONLY if you have good reason to do so (desktops & laptops). If you are going to be using your PC at frequent intervals, or expect network traffic (especially at work), then leave it on, more for the convenience than anything else. Otherwise shut it down.
I happen to use my PC a lot so I leave it on all day and turn it off at night. Same goes with a laptop if I ever see the need for one. You shouldn't have any cooling problems with a well built laptop.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?