"There's no real reason to shut down a computer UNLESS either: 1) Power usage is an issue 2) You have been told to restart because of an install/update 3) Something has gone seriously wrong. " #4 should be: "Unless common sense is involved". In my opinion it's just reasonable to turn the thing off, when I've stopped using it for the day. If the machine is locked, not hibernating, doesn't the HDD spin all the time (they used to)? They last for a certain amount of hours, and a week of spinning in vain is clearly off from it's active life span, is it not? One excuse for not shutting down is that those usually get broken during the boot,but it's a lame excuse I think. In the tube-display era having only the display switched on 24/7, even though the PC was off, could cut the life span of the displays by 30-50%. I don't know how it is with the LCDs. If a big state office, with thousands of computers was caught having PCs running 24/7, it would be accused for wasting tax payers money and straining the environment. Carrying the tiny responsibilities starts from each of us. We're sucking the globe dry anyway...(stops preaching, slightly blushed).