Vista - deos sleep mode keep the HD running?

i was told that hard drives in laptops spin when in use (i am no genius when
it comes to computers) and i want a quick startup time but i have been
hearing bad things about hibernation mode in vista...my question is....is it
safe for the computer to put into sleep mode, then put my laptop in my
backpack and go to class and what not? i don't want it to scratch the hard
disc, and i don't know if it is safe to let it be in safe mode for days at a
time (will it drain the battery?)
i have asked questions on here before and the responses from all of you were
VERY helpful!!!

thanks to all that help!!!

TECHNICALLYanIDIOT!!! <TECHNICALLYanIDIOT@xxxxxx>
wrote:
When it's in sleep mode, your computer's monitor and disk drives are
shut down. Current continues to flow to RAM memory, so that its
contents are preserved. This allows it to wake up quite quickly, but
because there is a small current drain, you can't do it forever.

When you hibernate your computer, the contents of RAM are written out
to a disk file, then the computer turns itself off. No current is
used, so you can leave it hibernated as long as you want. Because it
has to read all that data from the disk drive, restarting from
hibernation takes a bit longer than restarting from sleep.

You're not going to scratch the disk drives either way (unless you
*really* bash your backpack around)! Sleeping it for several days will
drain the battery. I think that if the battery gets too low, the
computer will automatically hibernate.

One warning: I don't understand why this happened, but I recently left
my computer in sleep mode for a couple of days. I don't normally do
this, but this time I put it down and forgot about it. It restarted
fine, but a couple of minutes later, the screen went gray and the
machine locked up hard. I had to cut power (push and hold power
button) to shut it down, then restart it. That doesn't mean it will
happen to you, but strange things do happen....

--
Tim Slattery
MS MVP(Shell/User)
Slattery_T@xxxxxx
http://members.cox.net/slatteryt