@Guspaz: I know. It was a rethoric

. It was just to state clearly (specially to ask1about) that hibernate won't give you problems because of someone taking the battery out.

@Fallen Angel: once more, the contents are
not stored in the RAM, as you said ('it loads window's data from the ram'), but from the hard drive.
edited: if the contents were in the RAM, failing to provide energy to the laptop would result in missing data, since the RAM we use is volatile.
@YinYang: I always use hibernate, and I also don't know why someone would not do that (
edited: i know it was already discussed. No need to reply only because of that...). However, maybe it's just me, because I realize hibernation takes up space on the HD (exactly the amount of the RAM). The RAM, IIRC, is stored, on windows, on a file called hiberfil.sys, on the root (top-level) folder of the drive.
Also, things not always work properly, as already stated here lots of times. People here say that it needs a reboot to work again, but, honestly (and personally), I never had a problem that couldn't be solved with a logoff-logon. Mostly, these errors are icons not beeing shown on the taskbar area and also CPU speed problems (at least here)...
Not that I never turn off. Sometimes (quite often) I do, just to be on the safe side... don't know why, but i do... and backed by some people, it seems it's not a bad thing to do.