Standby and hibernation modes behave differently between Windows XP and Windows Vista (and 7, I believe) Standby puts the computer in a low power state, but still use electricity to power the RAM to keep the information there. If the power is completely out – say your dog use a screwdriver to pry out the battery – then the computer will have to be rebooted. Hibernation is more like a shutdown. It saves the information stored in RAM to the hard disk, and then turns off the computer completely. As result, it takes longer than standby. However, the state of the computer is safe from your dog.
In Windows Vista, hibernation is no longer directly supported. There is only “sleep,” which by default behaves like standby. You can enable a hybrid sleep mode, which is essentially a combination of first going standby and then switch to hibernation when the battery becomes low. You can enable this hybrid sleep mode by using the following command (make sure you elevated your command prompt to admin level via "run as administrator”):
powercfg -h onFor those who prefer running the hibernation mode directly, this website has direction to create a shortcut to do just that. Essentially, you create a shortcut that runs:
rundll32.exe powrprof.dll,SetSuspendState 0,1,0Reference: Hibernate Shortcut – Vista Forums