Is it ok for a laptop to go into standby or hibernate instead of turning it off?
Placing your laptop or computer into a hibernation mode or standby mode instead of turning it off each time you're away from it will in no way harm it.
Why would I hibernate instead of turning my computer off?
When a computer is placed into hibernation mode all the open programs are left in a temporary storage. When the computer is turned back on you'll be able to resume were you left off much faster and will not have to wait for the computer to load.
But it saves power to turn off the computer.
According to Microsoft and Energy Star placing a Windows ME, 2000, XP, or Vista computer into hibernation mode will save almost as much power as turning it off. Unless of course you're also unplugging the computer and monitor each time you turn them off. However, to save as much power as possible Energy Star still recommends turning the computer off.
I'll save disk space by not using hibernate.
It's true, if you're hibernating your computer or hibernation is enabled it will use some of the space on your hard drive. If you are not hibernating your computer and need the disk space see, disable hibernation.