The Hibernate file (hiberfil.sys) will be the same size as the amount of physical memory you have installed. It's one of the first things I get rid of as I have 3GB of RAM and so would have a 3GB hiberfil.sys file. To turn it off, go to Start > Run, type in:
and click OK. Then into the Command window, type:
powercfg -h off
and press the Return key and reboot your computer. You can turn it on again by opening a Command window and using the command:
powercfg -h on
press the Return Key and reboot.