don't forget about turn off hibernation in win7 (if you dont use it)
to do that put this:
powercfg /hibernate off
in command window
and press enter
after that You can delete hiberfill.sys from system partition (usually drive C:/)
from my experience after that Win7 is more faster and less hard disk user 
Second thing is IF you got 4GB RAM and more
You can turn off pagefile.sys
and again Win7 is more willing to use RAM memory instead use hard disk drive
GOOD JOB Win7 creators !!!
greetings