Hiberfil.sys in Vista, how do I change the file's location?

The file which you mention is used for the Hibernate function of your computer. It is the same size as your computer memory, as the state of your computer which is stored in the computer memory is written to disk if you use the Hibernate function. If you do not use Hibernate, you can disable it, which will remove the file completely. If you wish to keep using the Hibernate function, then the file cannot be moved or removed. It needs to stay where it is, just like other required system files cannot be moved. Sorry.