By default in Windows 7, the size of the hidden protected OS hibernation file (C:\hiberfil.sys) is 75% of the total amount of installed RAM on your computer when hibernate is enabled. When hibernate is disabled, the space is available (free) until enabled again.
thanks. i have 8gb ram, so that's 6gb saved by my math. are there any other ways to reduce the amount of hard disk drive used for windows 7 pro? i don't recall being given options on things unnecessary, but maybe i missed it.